CHEMICAL  AND  GEOLOGICAL 


ESSAYS 


BY 


THOMAS  STEERY  HUNT,  LL.D., 

Fellow  of  the  Royal  Society  of  London  ;  Member  of  the  National  Academy  of  Sciences  of  the 

United  States,  the  Imperial  Leopoldo-Carolinian  Academy,  the  American 

Philosophical  Society,  the  American  Academy  of  Sciences, 

the  Geological  Societies  of  France  and  Belgium 

and  of  Ireland  ;  Officer  of  the  Order 

of  the  Legion  of  Honor, 

etc.,  etc.,  etc. 


SECOND  EDITION, 

EEVISED,    WITH    ADDITIONS. 


SALEM: 
S.    E.    GASSING. 

NATURALISTS'  AGEKCY. 

1878. 


EARTH 

SCIENCES 

UBRARY 


Entered  according  to  Act  of  Congress,  in  the  year  1874. 

BY  JAMES   B.   OSGOOD   &  CO., 
in  the  Office  of  the  Librarian  of  Congress,  at  Washington. 


COPYRIGHT,  1878,  BY  S.  E.  CASSINO. 

Jfei* 


UNIVERSITY  PRESS  :  WELCH,  BIGELOW,  &  Co., 
CAMBRIDGE. 


TO 

JAMES   HALL, 

IN  RECOGNITION  OF  MANY  YEARS  OF  FRIENDSHIP, 

Cfjts  Folutne  is 

BY 

THE    AUTHOK. 


256268 


PREFACE. 


IN  choosing  from  a  large  number  the  following  papers  for 
republication,  it  may  be  well  to  state  the  considerations  which 
have  guided  the  author  in  his  selection.  His  researches  and 
his  conclusions  as  to  the  chemistry  of  the  air,  the  waters,  and 
the  earth  in  past  and  present  times,  the  origin  of  limestones, 
dolomites,  and  gypsums,  of  mineral  waters,  petroleum,  and  me- 
talliferous deposits,  the  generation  of  silicated  minerals,  the 
theory  of  mechanical  and  chemical  sediments,  and  the  origin 
of  crystalline  rocks  and  vein-stones,  including  erupted  rocks  and 
volcanic  products,  cover  nearly  all  the  more  important  points 
in  chemical  geology.-  They  have,  moreover,  been  by  him  con- 
nected with  the  hypothesis  of  a  cooling  globe,  and  with  certain 
views  of  geological  dynamics,  making  together  a  complete 
scheme  of  chemical  and  physical  geology,  the  outlines  of  which 
will  be  found  embodied  in  essays  I.  —  XIII.  of  the  present 
collection.  It  was  at  one  time  proposed  to  rewrite  for  this 
volume  the  first  seven  of  these,  giving  them  a  more  connected 
form,  and  thereby  avoiding  some  little  repetition;  but  it  is 
thought  better  to  reproduce  them  in  the  shape  in  which  they 
originally  appeared,  and  this  chiefly  for  the  reason  that  they 
seem  to  the  author  to  have  a  certain  historic  value,  and  serve 
to  fix  the  dates  of  the  origin  and  development  of  views,  some 
of  which,  after  meeting  for  a  time  with  neglect  or  with  active 


VI  PREFACE. 

opposition,  are  now  beginning  to  find  favor  in  the  eyes  of  the 
scientific  world.  That  such  will  be  the  ultimate  fate  of  others 
herein  contained,  and  not  yet  generally  received,  the  author 
is  persuaded.  It  has  been  his  fortune  to  enunciate,  in  very 
many  cases,  views  for  which  his  fellow-workers  were  not  pre- 
pared, and  after  a  lapse  of  years  to  find  these  views  propounded 
by  others  as  new  discoveries  or  original  conclusions.  Natu- 
rally desirous,  however,  of  vindicating  his  claims  to  priority  in 
certain  of  these  matters,  he  feels  that  the  best  way  of  attain- 
ing this  result  is  to  reprint  the  original  essays.  It  should  be 
said  that  two  of  these,  namely,  IY.  and  XII.,  were  given  as 
popular  lectures,  and  are  thus  unlike  the  others  in  method 
and  style. 

The  reproduction  of  the  papers  on  the  Geology  of  the  Alps 
and  the  History  of  Cambrian  and  Silurian  requires,  it  is  con- 
ceived, no  explanation,  inasmuch  as,  apart  from  their  general 
interest,  they  serve  to  throw  great  light  upon  many  questions 
raised  in  the  essay  on  the  Geognosy  of  the  Appalachians  as  to 
the  origin  and  age  of  their  rocky  strata. 

As  regards  the  five  papers  which  are  placed  at  the  end  of  the 
volume,  the  author  reprints  them  for  the  reason  that,  incom- 
plete and  fragmentary  as  they  are,  they  have  a  certain  value  in 
the  history  of  chemical  theory;  and,  moreover,  contain,  in 
his  opinion,  the  germs  of  a  philosophy  of  chemistry  and  miner- 
alogy which  he  hopes  one  day  to  develop  himself  or  to  see 
developed  by  others. 

In  preparing  this  collection  for  the  press,  the  author  has  been 
compelled  by  the  limits  assigned  to  the  volume  to  omit  several 
papers  which  would  else  have  found  a  place  here,  and  to  abridge 
others.  In  some  cases,  paragraphs  have  been  rewritten  and 
additions  made,  which  are  distinguished  by  being  placed  in 
brackets.  Explanatory  notes  are  given,  and  introductory  and 


PREFACE.  VU 

historical  sketches  prefixed,  with  references  both  to  other  papers 
in  this  volume  and  to  many  which  have  been  omitted.  Eead 
with  these  aids,  and  with  the  help  of  the  table  of  contents  and 
index,  this  volume  will,  it  is  believed,  suffice  to  give  clear  and 
connected  notions  of  the  author's  views  on  the  various  questions 
herein  discussed. 

T.  s.  H. 

BOSTON,  Mass.,  September,  1874. 


PREFACE 

TO   THE   SECOND   EDITION. 


IN  revising  this  volume  for  a  new  edition,  it  was  felt  that 
the  introduction  of  any  changes  in  the  Essays  themselves 
would  be  at  variance  with  the  plan  of  the  work,  which  was  to 
preserve  in  their  original  form  certain  papers,  the  value  of 
which  is  in  part  historical.  The  author  has  therefore  con- 
fined himself  to  the  correction  of  typographical  errors  in  the 
text ;  but  takes  this  occasion  to  present  some  extended  com- 
ments and  critical  notes  upon  certain  geological  questions 
discussed  in  the  Essays,  with  regard  to  which  decided  progress 
has  been  made  since  the  publication  of  the  first  edition. 

On  pages  46  -  48  is  a  suggestion,  made  many  years  since, 
regarding  the  question  of  the  temperature  of  the  earth's  sur- 
face in  former  geological  periods,  which,  from  its  bearings, 
both  direct  and  indirect,  on  some  recent  geological  theories, 
calls  for  farther  notice.  From  the  great  amount  of  carbon 
and  hydrocarbons  of  organic  origin  found  in  the  rocky  strata 
of  the  earth,  it  has  long  been  inferred  that  the  atmosphere  of 
earlier  times  must  have  contained  a  large  quantity  of  carbonic 
dioxyd,  which  yielded  up  its  carbon  for  the  nutrition  of  the 
ancient  floras.  From  this  the  late  Major  Edwin  B.  Hunt 
concluded  that  the  atmosphere  in  former  periods  being  much 
denser  than  at  present,  the  temperature  at  the  earth's  surface, 


X  PREFACE. 

due  to  solar  radiation,  would  be  greater  than  now.  It  was 
subsequently  pointed  out  by  the  present  writer  that,  as  already 
shown  by  Tyndall,  the  relations  of  carbonic  dioxyd  to  radiant 
heat  are  such  that  a  quantity  of  this  gas  too  small  to  affect 
considerably  the  weight  of  the  atmospheric  column  would,  by 
preventing  the  loss  of  heat,  suffice  to  produce  a  tropical  tem- 
perature over  the  earth  at  the  sea-level. 

The  quantity  of  carbon  which^  has  been  removed  from  the 
air  by  vegetation  in  past  ages  is,  however,  very  considerable. 
In  a  communication  by  the  writer  to  the  American  Associa- 
tion for  the  Advancement  of  Science,  at  Buffalo,  in  1866,  it 
was  stated  that  the  whole  amount  of  free  oxygen  in  the  pres- 
ent atmosphere  is  no  more  than  sufficient  to  form  carbonic 
dioxyd  with  the  carbon  of  a  layer  of  coal  covering  the  globe 
one  meter  in  thickness,  and  that  the  aggregate  of  carbonaceous 
matter  in  the  earth's  crust  would  probably  much  exceed  this. 
Such  a  layer  of  coal,  of  specific  gravity  1.25,  would  have  a 
weight  equal  to  3,160,000  gross  tons  to  the  square  mile,  while 
Mr.  J.  L.  Mott,  in  a  communication  to  the  British  Association 
for  the  Advancement  of  Science,  in  1877,  estimates  the  total 
amount  of  carbonaceous  substances  in  the  earth  at  not  less 
than  3,000,000  tons  of  carbon  to  the  square  mile,  and  probably 
many  times  greater.  This  minimum  amount  of  pure  carbon 
is  equal  to  600  times  the  present  amount  of  carbonic  dioxyd 
in  the  atmosphere,  or  to  nearly  dne  fourth  its  entire  volume ; 
and,  inasmuch  as  the  fixation  of  carbon  by  vegetation  liberates 
a  corresponding  volume  of  oxygen,  would  represent,  according 
to  him,  a  greater  amount  of  this  gas  than  the  present  atmos- 
phere contains.  In  addition  to  this,  it  must  be  considered 
that  the  composition  of  the  various  hydrocarbonaceous  min- 
erals shows  a  deoxydation  not  only  of  carbonic  dioxyd  but  of 
water.  The  amount  of  liberated  oxygen  derived  from  water 


PREFACE.  xi 

equals,  for  the  various  coals  and  asphalts,  from  one  eighth  to 
one  fourth,  and  for  the  petroleums  one  half  of  that  set  free 
in  the  deoxydation  of  the  carbon  which  these  hydrocar- 
bonaceous  bodies  contain.  To  this  must  be  added  also  the 
oxygen  set  free  in  the  generation  of  metallic  sulphids  by  the 
deoxydation  of  sulphates,  which  is  effected  through  the  agency 
of  organic  matters,  and  indirectly  liberates  oxygen.  Against 
this  we  must  however  set  the  unknown  but  very  consid- 
erable amount  of  oxygen  absorbed  in  the  peroxydation  of 
ferrous  oxyd  liberated  in  the  decay  of  the  silicates  of  crys- 
talline rocks;  which  may,  perhaps,  serve  to  explain  the  dis- 
appearance from  the  air  of  the  whole  of  this  excess  of 
oxygen. 

The  terrestrial  vegetation  and  the  air-breathing  fauna,  which 
we  find  from  paleozoic  ages,  are,  it  is  unnecessary  to  remark, 
incompatible  with  an  atmosphere  holding  one  fourth  its  vol- 
ume of  carbonic  dioxyd,  and  the  difficulty  of  the  problem  is 
greatly  increased  when  we  consider  that  this  amount,  cor- 
responding to  the  carbon  fixed  in  the  earth's  crust  in  deoxy- 
dized  forms,  is  insignificant  when  compared  with  that  which 
has  been  absorbed  during  the  decomposition  of  silicated  rocks, 
and  is  now  fixed  in  the  form  of  limestones.  The  magnitude 
of  this  process  is  seen  when  we  consider  that  all  the  argil- 
laceous rocks  and  clays  of  the  stratified  formations  have  come 
from  the  decay  of  the  feldspars  and  other  silicates  of  the 
earlier  eozoic  terranes  through  the  intervention  of  carbonic 
dioxyd,  and  that  the  resulting  alkaline  and  earthy  carbonates 
are  now  represented  by  the  limestones  so  abundant  in  the 
earth's  crust.  It  was  shown,  in  the  author's  communication 
already  quoted,  that  a  layer  of  pure  limestone  covering  the 
earth's  surface  to  a  depth  of  about  twenty-eight  feet  (8.61 
meters)  corresponds  to  an  amount  of  carbonic  dioxyd  which, 


Xii  PEEFACE. 

if  set  free,  would  double  the  weight  of  the  present  atmos- 
phere, and  the  existence  of  great  limestone  and  dolomite 
formations,  many  hundred  feet  in  thickness,  at  different  geo- 
logical horizons  over  wide  areas,  will,  it  is  believed,  justify  the 
conclusion  that  the  earth's  crust  contains,  fixed  in  the  form 
of  carbonates,  an  amount  of  carbonic  dioxyd  which,  if  liberated 
in  a  gaseous  form,  would  be  equal  in  weight  to  at  least  two 
hundred  atmospheres  like  the  present  one.  A  portion  of 
this  carbonic  acid  was  doubtless  separated  at  an  early  period 
in  the  history  of  'our  globe,  since  the  limestones  of  the  eozoic 
rocks  are  of  considerable  thickness,  and  those  of  more  recent 
times  are  in  part  derived  from  the  solution  and  redeposition 
of  the  older  limestones. 

The  only  known  sources  of  carbonic  dioxyd,  apart  from 
combustion  and  respiration,  are  certain  terrestrial  exhalations 
of  the  gas,  probably  due  to  chemical  reactions  liberating  small 
portions  which  had  long  before  been  fixed  in  the  form  of  car- 
bonates. We  are  thus  forced  to  one  of  two  conclusions  :  either 
the  wholly  improbable  one  that  the  atmosphere  since  the  ap- 
pearance of  organic  life  on  the  earth  has  been  one  of  nearly 
pure  carbonic  dioxyd,  and  of  such  immense  extent  that  the 
pressure  at  the  surface  would  have  sufficed,  at  ordinary  tem- 
peratures, for  its  liquefaction ;  or  else,  the  atmosphere  being  so 
constituted  as  to  permit  vital  processes,  that  carbonic  dioxyd, 
as  fast  as  removed  by  chemical  action  at  the  earth's  sur- 
face, was  supplied  from  some  extra-terrestrial  source.  We 
may,  in  accordance  with  this  last  hypothesis,  admit  that  the 
atmosphere  is  not  terrestrial  but  cosmical,  and  that  the 
air,  together  with  the  water  surrounding  our  globe  (whether 
in  a  liquid  or  a  vaporous  state),  belongs  to  a  common  elas- 
tic medium  which,  extending  throughout  the  iuterstellary 
spaces,  is  condensed  around  attracting  bodies  in  amounts  pro- 


PREFACE.  Xlll 

portional  to  their  mass  and  temperature,  while  in  the  regions 
most  distant  from  these  centres  of  attraction,  this  universal 
atmosphere  would  exist  in  the  state  of  greatest  tenuity. 
Such  being  the  case,  a  change  in  the  atmosphere  of  any  globe, 
whether  by  the  absorption  or  disengagement  of  any  gas  or 
vapor,  would,  by  the  laws  of  diffusion  and  of  static  equilibrium, 
be  felt  everywhere  throughout  the  universe ;  and  the  fixation 
of  carbonic  dioxyd  at  the  surface  of  our  planet  would  not  only 
bring  in  a  supply  of  this  gas  from  the  worlds  beyond,  but,  by 
reducing  the  total  amount  of  it  in  the  universal  atmosphere, 
would  diminish  the  atmospheric  pressure  at  the  surface  of  our 
own  and  of  other  worlds. 

This  hypothesis  is  not  altogether  new.  Sir  William  R. 
Grove,  in  1842,  put  forth  the  notion  that  the  medium  of  heat 
and  light  may  be  "  an  universally  diffused  matter,"  and  subse- 
quently, in  1843,  in  his  celebrated  Essay  on  the  Correlation 
of  Physical  Forces,  in  the  chapter  on  Light,  concludes,  with 
regard  to  the  atmosphere  of  the  sun  and  the  planets,  that 
there  is  no  reason  why  these  atmospheres  "should  not  be, 
with  reference  to  each  other,  in  a  state  of  equilibrium.  Ether, 
which  term  we  may  apply  to  the  highly  attenuated  matter 
existing  in  the  interplanetary  spaces,  being  an  expansion  of 
some  or  all  of  these  atmospheres,  or  of  the  more  volatile  por- 
tions of  them,  would  thus  furnish  matter  for  the  transmission 
of  the  modes  of  motion  which  we  call  light,  heat,  etc.,  and 
possibly  minute  portions  of  these  atmospheres  may,  by  gradual 
accretions  and  subtractions,  pass  from  planet  to  planet,  form- 
ing a  link  of  material  communication  between  the  distant 
monads  of  the  universe."  Subsequently,  in  his  address  as 
President  of  the  British  Association  for  the  Advancement  of 
Science,  in  1866,  Grove  farther  suggested  that  this  diffused 
matter  might  be  a  source  of  solar  heat,  inasmuch  as  the  sun 


xiv  PREFACE. 

may  "  condense  gaseous  matter  as  it  travels  in  space,  and  .so 
heat  may  be  produced." 

In  1870,  Mr.  W.  Mattieu  Williams,  who  does  not  seem  to 
have  been  acquainted  with  these  views,  published  his  in- 
genious work  entitled  "  The  Fuel  of  the  Sun,"  which  is  little 
more  than  a  development  of  the  suggestions  of  Grove.  The 
source  of  solar  heat,  according  to  him,  is  the  condensation  by 
the  sun  of  the  attenuated  matter  or  ether  everywhere  encoun- 
tered by  that  body  in  its  motion  through  interstellary  space. 
The  heat  which,  from  sun  and  planets,  is  radiated  into  space,  is 
thus  first  absorbed  by  the  ether,  and  then  again  concentrated 
and  redistributed  by  the  sun. 

Dr.  P.  Martin  Duncan,  in  his  address  as  President  of  the 
Geological  Society  of  London,  in  May,  1877,  without  noticing 
the  priority  of  Grove,  has  adopted  from  Williams  the  notion  of 
a  cosmical  atmosphere,  but  supposes  that  the  sun,  in  virtue 
of  its  greater  mass,  is  slowly  attracting  to  itself  the  greater 
part  of  the  earth's  atmospheric  envelope.  From  this  view  he 
proceeds  to  deduce  important  geological  considerations,  con- 
ceiving that,  from  the  greater  height  of  the  terrestrial  atmos- 
phere, which,  according  to  his  hypothesis,  must  have  prevailed 
in  former  ages,  there  would  have  resulted  a  higher  tempera- 
ture at  the  earth's  surface,  more  aqueous  vapor,  a  more  equa- 
ble climate,  and  a  prolonged  twilight  at  the  poles.  From  a 
more  abundant  precipitation  greater  sub-aerial  denudation 
would  follow,  and  although  local  glaciation  of  high  mountains 
might  occur,  the  existence  of  masses  of  ice  at  the  earth's 
surface,  or  for  some  thousands  of  feet  above  it,  would  be 
impossible. 

If,  however,  the  principles  which  have  been  already  ad- 
vanced are  correct,  it  is  not  to  solar  attraction  that  we  arc 
to  attribute  a  progressive  diminution  in  the  height  of  the 


PREFACE.  XV 

atmospheric  column,  but  to  the  various  processes  going  on  in 
the  worlds,  whereby  the  atmospheric  elements  are  condensed 
in  the  form  of  liquid  water  or  fixed  as  hydrates,  oxyds,  or 
carbonates.  The  operation  of  such  processes  in  our  own  and 
other  planets  in  past  ages  must  have  produced  a  considerable 
refrigeration  of  climate  by  reducing  the  weight  of  the  atmos- 
phere, and  a  still  more  marked  result  of  the  same  kind  by 
diminishing  the  proportion  of  carbonic  dioxyd  contained 
therein,  as  has  already  been  pointed  out. 

Two  questions  here  present  themselves  in  connection  with 
the  problem  of  the  earth's  climate  from  the  appearance  of 
terrestrial  vegetation  until  now  :  1.  Has  the  mean  annual 
temperature  of  the  globe  during  this  period  ever  been  less  1 
2.  Has  it  ever  been  greater  than  at  present  1  It  is  shown  by 
paleontological  evidence  that  a  very  warm  or  subtropical 
climate  prevailed  over  the  arctic  regions  during  the  carbonifer- 
ous, triassic,  Jurassic,  and  lower  cretaceous  times,  following 
which  we  find  in  the  upper  cretaceous  a  commencement  of 
refrigeration,  although  until  the  close  of  the  miocene  a  vege- 
tation like  that  now  characterizing  the  middle  temperate 
zone  flourished  in  far  northern  latitudes.  After  this  came  the 
cold  of  the  pliocene  age,  which,  with  some  variations,  has 
continued  until  now.  That  the  arctic  cold  has  at  times  ex- 
tended over  certain  continental  areas  farther  southward  than 
at  present,  is  undoubted ;  but  this  —  the  mean  annual  tem- 
perature of  the  globe  being  the  same  as  now  —  might  result 
from  changed  geographical  conditions.  A  new  distribution  of 
land  and  water  might  bring  back  again  the  reindeer  to  France, 
or  give  to  Labrador  the  climate  of  Ireland.  More  than  this, 
geographical  changes  are  conceivable  which,  permitting  the 
influx  of  warm  currents  into  the  polar  seas,  would  create 
even  there  an  insular  climate  of  exceeding  mildness.  The 


XVI  PREFACE. 

studies  of  Nordenskibld  have,  however,  shown  that  a  warm 
climate  prevailed  there  in  the  carboniferous  age  over  a 
great  area  of  land,  which  supported  a  colossal  vegetation  not 
unlike  that  then  flourishing  in  the  intertropical  climates  of 
the  earth.  It  is  inconceivable  that,  with  an  atmosphere  con- 
stituted like  that  of  the  present  day,  any  geographical  condi- 
tions could  maintain  during  the  long  winter  nights  such  a 
climate  in  insular  regions,  and  still  less  over  a  continental  area 
within  the  polar  circle.  We  are  therefore  forced  to  the  conclu- 
sion that  geographical  changes,  though  a  true  cause  of  local 
variations  of  climate,  and  adequate  to  explain  the  greater 
refrigeration  of  certain  areas  since  the  commencement  of  the 
pliocene,  are  not  sufficient  to  account  for  the  warmer  climates 
of  previous  ages ;  and  we  conclude  that  the  cause  of  these  is 
to  be  found  in  the  former  greater  volume  and  different  chemi- 
cal constitution  of  the  atmosphere,  as  already  set  forth. 

This  view  is  opposed  to  the  hypothesis  maintained  by  many 
geologists  of  an  alternation  of  warm  and  glacial  climates  at 
the  surface  of  the  earth,  repeated  from  the  earlier  times. 
Dawson  and  Heer,  however,  from  the  study  of  the  fossil  floras 
found  in  arctic  regions  from  the  Devonian  to  the  miocene, 
conclude  that  paleontology  affords  no  evidence  of  such  a  con- 
dition of  things,  and  the  observations  of  McCoy,  Hector,  and 
Hutton  in  the  southern  hemisphere  lead  them  to  similar  con- 
clusions. The  nursery  of  these  successive  northern  floras 
appears  to  have  been  in  the  arctic  regions,  and  their  spread 
southward  would,  according  to  Dawson,  be  due  to  continental 
elevations,  bringing  about,  at  irregular  periods,  a  cooler  cli- 
mate in  the  northern  temperate  zone.  It  may  even  be 
conceived,  as  well  remarked  by  J.  F.  Campbell,  that  such  ele- 
vations might  bring  large  areas  of  the  earth's  surface  into  the 
region  of  perpetual  frost,  thus  giving  rise  to  local  glacial 


PREFACE.  XV11 

phenomena,  while  a  warm  climate  prevailed  everywhere  at 
the  sea-level.  Nordenskiold  declares  that  he  sought  in  vain 
for  evidences  of  ice-action  in  the  various  sedimentary  deposits 
of  Spitzbergen. 

In  regard  to  a  suggested  explanation  of  former  climatic 
conditions,  the  author  may  be  permitted  to  quote  the  follow- 
ing language  used  by  him  in  1876.  "Recent  speculations 
have  revived  the  old  notion  of  a  possible  change  of  the  earth's 
axis  of  rotation,  as  a  way  of  explaining  this  change  of  arctic 
climate;  but  such  a  phenomenon  is  astronomically  improbable, 
and  is  also  opposed  by  the  fact  that  the  direction  of  the 
oceanic  currents,  which  are  guided  by  the  earth's  rotation, 
appears,  from  the  distribution  of  marine  sediments,  to  have 
been  the  same  since  very  early  periods."  *  Dawson  has  since 
urged  the  same  argument,  and  reinforced  it  by  recalling  the 
fact  that  the  southward  migrations  of  successive  floras,  not  less 
than  the  lines  of  distribution  of  mechanical  sediments  in  past 
ages,  show  that  from  early  paleozoic  time  the  general  courses 
of  the  oceanic  currents,  and  consequently  the  position  of  the 
earth's  axis,  have  not  changed. 

In .  connection  with  the  hypothesis  of  a  universal  atmos- 
phere may  be  mentioned  a  speculation  which  was  put  forth 
by  the  author  in  an  address  delivered  by  him  in  July,  1874, 
at  the  grave  of  Priestley,  in  Northumberland,  Pennsylvania, 
entitled  "  A  Century's  Progress  in  Theoretical  Chemistry," 
and  published  in  the  American  Chemist  for  that  year  (vol.  V., 
pp.  46-51).  An  extract  therefrom,  under  the  title  of  "Celestial 
Chemistry,"  appeared  in  the  Popular  Science  Monthly  (vol. 
VII.,  p.  420).  In  that  address,  after  referring  to  the  results  of 
the  spectroscopic  study  of  the  stars,  and  to  the  increase  in  the 
chemical  complexity  of  their  spectra  which  appears  in  passing 
from  the  white  to  the  yellow  and  red  stars,  it  was  said  :  — 
*  Harper's  Annual  Record  of  Science  for  1876,  p.  cii. 


XVlil  PKEFACE. 

"  If,  in  accordance  with  the  nebular  hypothesis,  we  look 
upon  these  different  types  of  stars  as  representing  successive 
stages  in  the  process  of  condensation  from  nebula  to  planet, 
we  may  also  see  in  them  a  gradual  evolution  of  the  more  com- 
plex from  the  simpler  forms  of  matter  by  a  process  of  celestial 
chemistry.  Such  was  the  view  put  forward  by  F.  W.  Clarke, 
in  January,  1873,*  and  some  months  later  by  Lockyer,  who 
has  reiterated  and  enforced  these  suggestions,  and  moreover 
connected  them  with  the  speculations  of  Dumas  on  the  com- 
posite nature  of  the  elements I  ventured  in  1867, 

while  speculating  on  the  phenomena  of  dissociation,  to  remark 
that,  although  from  the  experiments  of  the  laboratory  we  can 
only  conjecture  the  complex  nature  of  the  so-called  elementary 
substances,  we  may  expect  that  their  '  further  dissociation  in 
stellar  or  nebulous  masses  may  give  us  evidence  of  matter  still 
more  elemental.' "  t 

The  green  line  in  the  spectrum  of  the  solar  chromosphere, 
which  has  been  supposed  to  show  therein  the  existence  of  a 
hitherto  unknown  gaseous  element,  was  then  noticed,  and  it 
was  added  :  "  Is  it  not  possible  that  we  have  here  that  more 
elemental  form  of  matter  which,  though  not  seen  in  the. nebu- 
lae, is  liberated  by  the  intense  heat  of  the  solar  sphere,  and 
may  possibly  correspond  to  the  primary  matter  conjectured 
by  Dumas,  having  an  equivalent  weight  one  fourth  that  of 
hydrogen1?  Mention  should  also  be  made  of  the  unknown 
element  conjectured  by  Huggins  to  exist  in  some  nebulae. 
This  conception  of  a  first  matter,  or  Urstoff,  has  also  been 
maintained  by  Hinrichs,  who  has  put  forward  an  argument 
in  its  favor  from  a  consideration  of  the  wave-lengths  in  the 
lines  of  the  spectra  of  various  elements.'* 

*  Evolution  and  the  Spectroscope  :  Popular  Science  Monthly,  volume  II., 
page  320. 

t  See  page  37  of  the  present  volume. 


PREFACE.  XIX 

"It  is  curious  in  this  connection  to  note  that  Lavoisier 
suggested  that  hydrogen,  nitrogen,  and  oxygen,  with  heat  and 
light,  might  be  regarded  as  simpler  forms  of  matter  from 
which  all  others  were  derived.  The  nebulae,  which  we  con- 
ceive as  condensing  into  suns  and  planets,  show  us  only  two 
of  the  three  elements  of  our  terrestrial  envelope,  which  is 
made  up  of  air  and  aqueous  vapor.  If  now  we  admit,  as  I 
am  disposed  to  do,  with  [Sir  William  R.  Grove  and]  W.  Mat- 
tieu  Williams  that  our  atmosphere  and  ocean  are  not  simply 
terrestrial  but  cosmical,  and  are  a  portion  of  the  medium 
which,  in  an  attenuated  form,  fills  the  interstellary  spaces, 
these  same  nebulae  and  their  resulting  worlds  may  be  evolved 
by  a  process  of  chemical  condensation  from  this  universal 
atmosphere,  to  which  they  would  sustain  a  relation  somewhat 
analogous  to  that  of  clouds  and  rain  to  the  aqueous  vapor 
around  us.  This,  though  it  may  be  regarded  as  a  legitimate 
and  plausible  speculation,  is  at  present  nothing  more,  and  we 
may  never  advance  beyond  conjecture  as  to  the  relations  of 
the  various  forms  of  so-called  elemental  matter,  and  to  the 
processes  which  govern  the  evolution  of  the  starry  spheres." 

The  Taconic  rocks  have  of  late  been  the  object  of  much 
study  on  the  part  of  the  author,  leading  him  to  conclude  that 
what  has  been  said  of  them  in  Essay  XIII.  Part  1,  and  in 
Essay  XV.  Part  3,  is  true  only  of  that  portion  wfcich  Emmons 
at  first  included  in  the  upper  part  of  his  Taconic  system  un- 
der the  general  name  of  the  Taconic  slates,  but  in  1855  sepa- 
rated from  the  underlying  portions,  and  described  as  the 
Upper  Taconic  series.  This  is  no  other  than  the  Quebec 
group  of  Logan,  which  is  the  northward  prolongation  of  the 
Taconic  slates  from  eastern  New  York.  The  rocks  in  the 
Hudson  valley,  to  which  Mather,  in  his  Fourth  Annual  Report 
on  the  Geology  of  New  York  (in  1840),  gave  the  name  of  the 


XX  PREFACE. 

Hudson-River  slates  or  the  Hudson  slate  group,  included  these 
Upper  Taconic  rocks,  together  with  portions  of  strata  holding 
the  fauna  of  the  upper  members  of  the  Champlain  division. 
The  strata  of  this  region,  and  of  its  extension  north  and 
south,  including  the  western  border  of  the  whole  Atlantic 
belt,  from  the  Gulf  of  St.  Lawrence  to  Alabama,  have,  as  is 
well  known,  a  general  high  dip  to  the  eastward,  attended  with 
many  dislocations,  folds,  and  inversions ;  as  a  result  of  which 
the  newer  sediments  appear  to  pass  beneath  the  older  ones, 
and  even  beneath  the  still  more  ancient  crystalline  rocks  of 
the  belt,  giving  rise  to  some  of  the  most  perplexing  problems 
in  American  geology. 

The  fauna  of  the  Upper  Taconic  rocks,  including  the  forms 
found  at  Troy,  New  York,  at  Georgia,  Vermont,  and  at  Phil- 
lipsburg,  Point  Levis,  and  Bic,  in  the  province  of  Quebec, 
presents,  as  far  as  known,  nothing  lower  than  the  Menevian 
horizon,  and  belongs  to  the  Lower  and  Middle  Cambrian  of 
Sedgwick.  The  quartzites  and  magnesian  limestones  around 
the  Adirondack  region,  and  in  the  geographically  similar  area 
of  the  Upper  Mississippi,  which  are  generally  included  under 
the  names  of  the  Potsdam  sandstone  and  the  Calciferous  sand- 
rock,  or  Lower  Magnesian  limestone,  appear,  in  the  present 
state  of  our  knowledge,  to  have  been  deposited  during  the 
Upper  Taconic  period. 

The  whole  of  these  rocks  are  wanting  along  a  great  part  of 
the  northern  outcrop  of  the  Siluro-Cambrian  in  Canada,  where 
the  limestones  of  the  Trenton  group  repose  unconformably 
upon  crystalline  eozoic  (pre-Cambrian)  rocks,  and  moreover 
appear  as  outliers  still  farther  north,  resting  upon  these.  The 
Chazy  limestone,  a  formation  comparatively  limited  in  its 
distribution,  appears  by  its  fauna  to  connect  the  Cambrian 
rocks  with  the  Siluro-Cambrian,  represented  by  the  Trenton 


PREFACE.  XXI 

limestone  and  the  succeeding  Cincinnati  series,  which  includes 
the  Utica  slates  and  the  Loraine,  or  Pulaski  shales.  These, 
passing  from  Ontario  southeastwards,  along  the  west  side  of 
the  Adirondacks,  become  thinner,  and,  according  to  Conrad 
and  Vanuxem,  disappear  entirely  in  the  Mohawk  valley.  The 
Pulaski  shales  are  said  by  the  latter  to  be  underlaid  in  this  re- 
gion by  the  Frankfort  shales  and  sandstones  which,  after  the 
disappearance  of  the  Pulaski  shales,  form  the  surface-rock  east- 
ward to  the  Hudson,  and  were  regarded  as  the  lower  portion 
of  the  Hudson-River  slate  group,  then  supposed  to  overlie  the 
Trenton  limestones.  According  to  the  later  determinations 
of  Emmons  these  slates  are  Upper  Taconic,  and,  the  Trenton 
limestone  being  absent,  the  Loraiue,  the  upper  member  of  the 
Siluro-Cambrian,  is  found  in  outliers,  resting  unconformably 
upon  these  Upper  Taconic  (Cambrian)  slates. 

The  Oneida  conglomerate  and  sandstone  (which  forms  the 
base  of  the  true  Silurian  in  New  York  and  in  Pennsylvania) 
rests  upon  the  Loraine  shales  near  Lake  Ontario ;  but  where 
these  disappear,  to  the  southeast,  lies,  in  Oneida  County,  upon 
the  Frankfort  slates.  If  these  latter  are  really  Cambrian,  the 
whole  of  the  Siluro-Cambrian  would  be  wanting  in  this  region. 
In  the  eroded  anticlinal  valleys  west  of  the  Susquehanna 
River,  where  the  whole  of  the  Siluro-Cambrian  is  present, 
the  passage  from  the  Upper  Cambrian  (Cincinnati)  shales  into 
the  Silurian  sandstones  is  gradual,  and  there  is  no  strati- 
graphical  break,  although,  as  shown  by  Rogers,  such  an  inter- 
ruption occurs  between  these  same  sandstones  and  the  under- 
lying (Frankfort)  slates  along  the  northwest  border  of  the 
great  Appalachian  valley. 

The  Lower  Taconic  series  of  Emmons,  embracing  in  ascend- 
ing order  (1)  granular  quartz  rock,  (2)  the  Stockbridge  lime- 
stone with  its  interstratified  and  overlying  micaceous  schists, 


PREFACE. 


and  (3)  argillites,  including  roofing-slates,  constitutes  a  dis- 
tinct geological  horizon  of  rocks  essentially  crystalline,  having 
an  aggregate  thickness  of  about  five  thousand  feet.  These  are 
found  resting  alike  on  Laurentian,  Huronian,  and  Montalban 
strata,  and  are  overlaid,  probabry  unconformably,  by  the  Cam- 
brian (Upper  Taconic).  In  opposition  to  this  view  of  the  age 
of  the  Lower  Taconic,  which  was  that  originally  put  forward 
by  Emmons,  it  was  maintained  by  H.  D.  Rogers  that  the  lime- 
stones of  the  series  are  of  the  age  of  the  Calciferous  and 
Chazy  ;  by  Mather,  and  later  by  Dana,  that  they  are  Trenton  ; 
by  Adams,  and  others,  that  they  are  either  Lower  Helderberg 
or  Devonian  ;  and  finally,  by  Logan,  that  they  are  the  Levis 
limestones  of  the  Upper  Taconic,  —  in  all  cases  modified  by 
so-called  metamorphic  agency. 

Of  these  four  irreconcilable  views,  each  one  in  its  turn  has 
been  plausibly  defended  upon  the  ground  of  apparent  super- 
position to,  or  of  association  with,  fossiliferous  strata  of  vari- 
ous ages,  in  some  one  or  more  localities.  All  of  these  hypoth- 
eses are,  however,  in  the  author's  opinion,  equally  untenable, 
and  the  true  position  of  these  limestones,  as  maintained  by 
Emmons,  is  believed  to  be  inferior  to  the  Upper  Taconic  or  to 
the  Potsdam  sandstone.  They  are  apparently  identical  with 
the  great  limestone  series  which,  in  Hastings  county,  Ontario, 
underlies  unconformably  the  Trenton  group  of  limestones, 
and  near  St.  John,  New  Brunswick,  is  beneath  the  Menevian 
slates.  Whether  these  Lower  Taconic  limestones  and  slates, 
with  their  underlying  quartzites,  are  the  equivalents  of  the 
basal  beds  of  the  Cambrian  in  Scandinavia  is  not  certain,  and 
in  view  of  their  great  geological  importance  in  North  America, 
it  seems  proper,  while  referring  the  Upper  Taconic,  as  has 
already  been  done,  to  the  Cambrian,  to  preserve  for  the  lower 
group  the  original  name  of  Taconic  or,  better,  Taconian. 


PEEFACR  XXLLL 

The  rocks  of  the  Taconian  series,  though  in  part  detrital, 
are,  as  already  said,  essentially  crystalline,  and  although  dis- 
tinct alike  from  the  Montalban,  Huronian,  and  Laurentian 
series,  which  succeed  them  in  descending  order,  have  certain 
lithological  resemblances  with  each  of  these.  Mather,  whose 
views  were  adopted  without  question  by  a  great  number  of 
American  geologists,  supposed  all  of  these  unlike  groups  of 
rocks  to  be  nothing  more  than  Cambrian  and  Siluro-Cambrian 
strata,  constituting  the  Champlain  division  of  the  New  York 
system.  These,  including  the  succession  from  the  base  of  the 
Potsdam  to  the  summit  of  the  Loraine,  were  supposed  to  have 
been  modified  in  a  greater  or  less  degree  by  intrusive  rocks, 
and  by  unknown  agencies,  and  to  have  assumed,  in  different 
localities,  the  four  forms  of  the  Upper  Taconic,  the  true  Ta- 
conian, the  Montalban  and  Huronian  schists,  and  the  gneisses 
and  crystalline  limestones  of  the  Laurentian. 

To-day,  the  greater  part  of  this  extraordinary  hypothesis  is, 
by  most  geologists,  rejected ;  and  it  is  seen  that  the  dissimi- 
larities in  these  great  crystalline  series  cannot  be  explained 
by  supposing  them  to  result  from  subsequent  and  unlike 
changes,  in  different  areas,  of  one  and  the  same  uncrystalline 
paleozoic  series.  These  lithological  differences,  as  exhibited 
in  the  Highlands  of  the  Hudson,  in  the  crystalline  rocks  of 
the  Green  Mountains  and  White  Mountains,  and  in  those  of 
the  Taconic  hills,  correspond  to  four  great  series  of  pre-Cam- 
brian  rocks,  and  mark  as  many  successive  periods  in  eozoic 
time. 

As  we  pass  westward  beyond  the  influences  of  the  great 
Appalachian  disturbances  which  have  faulted,  folded,  and  in- 
verted alike  these  eozoic  formations  and  the  succeeding  paleo- 
zoic strata,  the  problem  of  the  relation  between  the  two 
becomes  much  less  complicated  and  more  readily  understood. 


XXIV  PREFACE. 

In  the  great  area  south  and  west  of  Lake  Superior,  -where  the 
Cambrian  formations  are  everywhere  undisturbed  and  unal- 
tered, it  is  clearly  and  unmistakably  seen,  as  Irving  has  so 
well  shown,  that  the  Laurentian,  Huroniau,  and  Montalban 
rocks  (there,  as  in  the  east,  greatly  folded  and  contorted)  are 
far  older  than  they.  The  Taconian,  with  its  characteristic 
limestones,  does  not  appear  in  this  northwestern  region,  but 
we  find  in  the  same  geological  interval  the  great  volcanic 
series  of  copper-bearing  strata  which  is  displayed  in  the 
Keweenaw  peninsula.  These  rocks,  successively  referred  by 
different  observers  to  the  mesozoic  period,  to  the  age  of  the 
Potsdam,  and  to  the  so-called  Quebec  group,  are  now  clearly 
shown  by  the  geological  survey  of  Wisconsin,  to  pass,  in  their 
southwestern  prolongation  through  that  state,  unconformably 
beneath  the  horizontal  fossiliferous  Lower  Cambrian  sand- 
stone, which  is  in  part  made  up  of  their  ruins.  This  great 
metalliferous  series,  which  the  author  has  distinguished  by  the 
name  of  Keweenian,  he  has  found  to  contain  in  its  conglom- 
erates the  gneisses  of  the  Laufentian,  the  petrosilexes,  green- 
stones, and  chloritic  schists  of  the  Huronian,  and  the  charac- 
teristic mica-schists  of  the  Montalban. 

The  Taconian  rocks,  which  are  conspicuous  in  the  great 
Appalachian  valley  from  Vermont  to  Alabama,  are  character- 
ized by  many  lithological  peculiarities.  The  magnesian  lime- 
stones of  the  series  sometimes  contain  serpentine  and  mica, 
often  finely  disseminated,  while  the  associated  schists  are 
sometimes  in  large  part  made  up  of  a  hydrous  mica.  Garnet, 
chlorite,  and  crystalline  oligist  and  magnetite  ores,  are  also 
found  abundantly  at  this  horizon,  and  the  whole  series  of 
quartzites,  limestones,  and  interstratified  schists  constitutes  a 
group'  very  distinct  in  its  lithological  characters  from  the 
older  crystalline  groups.  These  Taconian  rocks  include  great 


PREFACE.  XXV 

beds  both  of  carbonate  of  iron  and  pyrites,  and  from  the  oxy- 
dation  of  the  one'  and  the  other,  in  situ,  as  has  been  shown 
by  the  author,  have  been  derived  the  great  masses  of  brown 
hematite  ores  everywhere  found  along  the  outcrop  of  the 
series.  The  clays  often  accompanying  these  ores  are  the  re- 
sults of  the  decay  of  the  enclosing  crystalline  schists,  which, 
like  the  still  older  crystalline  strata  along  the  eastern  border 
of  the  Appalachian  valley,  are  in  many  places  decomposed 
to  considerable  depths. 

The  direct  evidences  of  life  in  these  Taconian  rocks  are  the 
marks  of  some  organic  form  which  have  been  described  under 
the  name  of  Scolithus,  and  appear  to  be  common  to  the 
quartzites  and  the  limestones ;  while  the  latter  contain,  more- 
over, fragments  of  an  undescribed  linguloid  shell.  In  some 
few  localities  the  existence,  among  areas  of  the  Taconian  lime- 
stones, of  strata  containing  recognized  paleozoic  forms  has  been 
noticed.  This  older  series  was,  however,  overlaid  both  by 
Cambrian  and  Siluro-Cambrian  strata,  which  were  afterwards 
subjected  to  disturbances  completely  inverting  the  order  of 
these  latter,  and  involving  at  the  same  time  in  their  folds 
and  dislocations  underlying  strata  alike  of  Taconian,  Montal- 
ban,  Huron ian,  and  even  of  Laurentian  age,  to  such  an  extent 
that  all  of  these,  in  their  turn,  have,  as  we  have  seen,  been 
regarded  as  altered  paleozoic  strata.  Thus,  in  repeated  in- 
stances, Siluro-Cambrian  rocks  are  overlaid  by  others  which 
are  clearly  Cambrian  sediments,  while  these  latter  are  found 
to  pass  beneath  the  crystalline  rocks  of  the  Atlantic  belt 
called  by  Logan  "  altered  Quebec  group"  (Cambrian).  These, 
however,  as  was  long  since  pointed  out  by  the  writer,  are  pre- 
Cambrian  rocks  of  Huroniau  age.  The  investigations  of  the 
geological  survey  of  Canada  within  the  last  two  years  have 
fully  vindicated  this  view,  as  it  was  set  forth  in  pages  276 


XXVI  PREFACE. 

and  408  of  the  present  volume.  In  the  limestones  and  slates 
referred  above  to  the  Taconian,  which,  in  Madoc,  Ontario,  lie 
between  the  Huronian  and  the  Trenton  (which  latter  rests 
upon  them  unconformably),  there  have  been  found  by  Daw- 
son,  besides  Scolithus-like  markings,  the  remains  of  Eozoon  not 
unlike  that  of  the  Laurentian. 

The  Alps,  where  similar  geological  accidents  to  those  of 
the  Atlantic  belt  in  North  America  involve  not  only  paleozoic 
but  mesozoic  and  even  cenozoic  strata,  have  been  the  object 
of  similar  hypotheses  to  that  of  Mather,  and  the  crystalline 
rocks  of  that  region  have  been,  in  turn,  assigned  to  every  one 
of  these  periods  (see  pages  334-346).  The  late  researches  of 
Gastaldi  and  others  have,  however,  shown  the  fallacy  of  these 
views,  and  established  a  complete  harmony  between  the  geol- 
ogy of  the  Alps  and  that  of  our  Atlantic  and  Mississippi 
regions.  At  the  base,  according  to  Gastaldi,  is  a  great  series 
of  gneisses,  often  granitoid  and  porphyroid,  associated  with 
quartzites,  graphite,  and  crystalline  limestones,  the  whole  of 
which  is  referred  by  him  to  the  Laurentian.  A  second  series 
of  great  thickness,  known  as  the  greenstone  or  pietri  verdi 
group,  consists  of  varieties  of  diabase  with  serpentine  and 
chloritic,  steatitic,  and  epidotic  strata,  associated  with  quart- 
zose  and  calcareous  schists. 

These  rocks,  which  are  widely  spread  in  northern  Italy, 
have  been  by  most  geologists  looked  upon  either  as  eruptive, 
or  as  contact-deposits  resulting  from  the  action  of  eruptive 
masses  upon  uncrystalline  sediments,  and  from  their  supposed 
stratigraphical  relations  have  been  assigned  to  very  different 
geological  ages,  from  the  eocene  to  the  Silurian.  Gastaldi, 
however,  concludes  that  the  pietri  verdi  are  not  eruptive,  but 
indigenous,  and  constitute  a  well-defined  series  of  great  thick- 
ness, pre-paleozoic  in  age,  resting  unconformably  upon  the 


PREFACE.  XXVU 

Laurentian,  and  referred  by  him  to  the  Huronian,  of  which  it 
has  all  the  characters.  To  this  succeeds  another  great  group 
consisting  of  quartzites  with  limestones  and  dolomites,  some- 
tunes  schistose  and  micaceous,  including,  near  the  summit, 
gypsum  and  anhydrite.  These  also  have,  in  turn,  been  as- 
signed to  various  geological  horizons  from  the  tertiary  down- 
ward, but,  according  to  the  same  observer,  are,  if  not  pre- 
paleozoic,  at  the  very  base  of  the  paleozoic  series.  Similar 
views  with  regard  to  the  crystalline  rocks  of  the  Alps  have 
been  arrived  at  by  Favre,  and  by  Giordano  and  Gerlach. 

The  Origin  of  Crystalline  Rocks  has  been  discussed  at  some 
length  in  this  volume,  where,  on  pages  285,  286,  the  two 
principal  hypotheses  proposed  to  account  for  the  mineralogical 
composition  of  such  rocks  are  concisely  stated.  The  first  of 
these  supposes  that  the  minerals  of  which  many  of  these 
rocks  are  composed  •"  have  resulted  from  an  alteration  of  pre- 
viously existing  minerals  of  plutonic  rocks,  often  very  unlike 
in  composition  to  the  present,  by  the  taking  away  of  certain 
elements  and  the  addition  of  certain  others."  This  change, 
which  in  the  individual  mineral  is  called  epigenesis  or  pseudo- 
morphism, is  designated  metamorphism  or  metasomatosis 
when  applied  to  rock-masses.  Ah  attempt  is  made  on  page 
295  to  give,  in  general  terms,  the  views  of  those  who  maintain 
this  hypothesis  of  the  origin  of  the  crystalline  schists ;  and 
the  extent  to  which  it  has  been  carried  by  certain  of  its  advo- 
cates is  fully  shown  on  pages  319,  320,  324,  325,  and  326. 

In  opposition  to  this  hypothesis,  which  supposes  that  the 
various  crystalline  silicated  rocks  have  been  derived  from  plu- 
tonic  masses  by  epigenic  changes,  effected  through  aqueous 
agencies,  is  that  maintained  by  the  author,  according  to  which 
the  crystalline  stratified  rocks  are  not  plutonic  but  neptunean 
in  origin,  and,  except  so  far  as  they  are  mechanical  sediments 


XXViii  PEEFACE. 

coming  from  the  chemical  or  mechanical  disintegration  of 
more  ancient  rock-masses,  "were  originally  deposited  as,  for 
the  most  part,  chemically  formed  sediments  or  precipitates,  in 
which  the  subsequent  changes  have  been  simply  molecular,  or 
at  most  confined  to  reactions,  in  certain  cases,  between  the 
mingled  elements  of  the  sediments."  This  view  is  illustrated 
at  length  on  pages  296-300,  where  it  is  applied  to  silicates 
such  as  serpentine,  talc,  chlorite,  hornblende,  pyroxene,  gar- 
net, and  epidote,  all  of  which  are  conceived  to  have  been 
"  formed  by  a  crystallization  and  molecular  rearrangement  of 
silicates  generated  by  chemical  processes  at  the  earth's  sur- 
face." The  formation  of  crystalline  feldspar  in  veins,  evidently 
of  aqueous  origin,  is  also  cited  as  throwing  light  on  the  genesis 
of  bedded  feldspathjc  rocks,  and,  finally,  the  aqueo-igneous 
fusion  of  neptunean  crystalline  strata  is  supposed  to  give  rise 
to  plutonic  masses  (pages  285,  317). 

Although  the  hypothesis  of  the  plutonic  and  epigenic  or 
metasomatic  origin  of  crystalline  rocks  still  counts  many  dis- 
ciples, the  doctrine  of  their  neptunean  origin  has  found  favor 
with  some  of  the  most  enlightened  students,  as  has  been 
shown  on  pages  304,  305,  316,  and  317.  Prominent  among 
these  is  Delesse,  who,  as  we  have  seen,  early  renounced  the 
plutonic  for  the  neptunean  theory  of  crystalline  rocks.  He 
has,  since  the  printing  of  the  first  edition  of  this  volume,  given 
further  expression  of  his  views  on  this  question  in  a  critical 
notice  of  the  writings  of  the  plutonists,  Von  Lasaulx  and  Knop. 
According  to  Von  Lasaulx  all  crystalline  rocks  have  been 
derived  from  the  primitive  crust  of  the  globe,  which  he  sup- 
poses to  have  been  of  a  granitic  character.  The  changes 
wrought  therein  have  consisted,  first,  in  the  mechanical  dis- 
integration of  portions,  and  their  conversion  into  sedimentary 
rocks,  and,  second,  in  chemical  alterations  alike  of  these  and 


PREFACE.  XXIX 

of  the  primitive  igneous  rock.  In  this  way  granite  or  gneiss 
has  been  converted,  by  the  loss  of  alkali,  successively  into 
mica-schists  and  argillite,  while  other  alterations  are  supposed 
to  have  given  rise  to  chloritic  and  talcose  minerals.* 

According  to  Knop  the  plutonic  rocks  themselves  have 
originated  by  a  similar  process  from  volcanic  products.  Gran- 
ite is,  in  his  view,  a  metasomatic  eruptive  rock,  derived  from 
a  trachytic  lava,  while  gneiss  is  formed  from  the  detritus  of 
trachyte  or  of  granite.  The  final  result  of  the  metasomatosis 
of  these  materials  (which  is  supposed  to  be  effected  through 
water,  at  great  depths,  under  heat  and  pressure)  is  a  mixture 
of  quartz  and  mica.  Doleritic  lavas  by  similar  transforma- 
tions give  rise  to  the  various  greenstones.  Knop  also  admits 
another  and  very  different  origin  for  crystalline  schists.  The 
kaolin  resulting  from  the  superficial  decomposition  of  granitic 
rocks  may,  by  the  fixation  of  alkali,  be  successively"  converted 
into  mica  and  feldspar,  so  that  a  plastic  clay,  by  such  a  pro- 
cess, might  be  changed  first  into  argillite,  then  into  mica- 
schist,  and  finally  into  a  gneiss.t  A  similar  hypothesis  has 
been  maintained  by  others,  and  the  introduction  of  foreign 
elements  in  solution  has  been  conceived  to  play  an  important 
part  alike  in  the  alteration  of  uncrystalline  sediments  and  of 
plutouic  rocks. 

These  latter  reactions  are  doubtless  possible  in  the  labora- 
tory, but  the  assumption  that  they,  or  the  metasomatic 
changes  imagined  by  Von  Lasaulx  and  Knop,  are  concerned 
in  the  genesis  of  the  crystalline  rocks  is  a  gratuitous  hypothe- 
sis, meriting  the  epithet  of  "  me"tamorphisme  a  1'outrance," 
given  by  Delesse.  In  opposition  to  the  views  of  metasoma- 
tosis, this  writer  asserts  that  "the  varied  characters  of  the 

*  Poggemlorf  s  Annalen,  vol.  167,  page  304. 

f  Neues  Jahrbuch  fur  Mineralogie,  1872,  pages  388  and  490. 


XXX  PKEFACE. 

crystalline  schists  are  not  due  to  their  having  passed  through 
a  greater  or  less  number  of  metamorphoses,  but,  on  the  con- 
trary, depend  essentially  upon  the  primitive  composition  of 
the  sediments  from  which  they  are  formed,  and  also  upon  the 
development  of  their  crystalline  structure."  He  then  pro- 
ceeds, in  accordance  with  the  author's  view,  to  consider  how, 
owing  to  the  different  chemical  composition  of  these  sedi- 
ments,«there  have  been  formed,  in  one  case,  feldspathic  rocks, 
in  another  hornblende  and  pyroxene,  in  another  serpentine, 
talc,  and  chlorite,  and  in  still  others  andalusite,  cyanite, 
staurolite,  and  micas. 

Von  Lasaulx,  from  the  microscopic  study  of  a  porphyritic 
protogine  and  its  contiguous  talcose  and  micaceous  schists, 
concludes  that  these  have  resulted  from  an  alteration,  in  place, 
of  portions  of  the  porphyry ;  but  Delesse,  with  reason,  main- 
tains an  original  difference  in  the  rocks  both  in  composition 
and  in  structure,  and  further  remarks  that  the  microscopic 
study  of  minerals  and  rocks,  while  rendering  important  ser- 
vices, "  has  greatly  contributed  to  the  rise  of  geological  theo- 
ries which  appear  to  be  inadmissible,  particularly  as  regards 
metamorphism,  showing  how  much  reason  De  Saussure  had 
to  say  that  mountains  should  not  be  studied  with  microscopes." 

With  regard  to  the  hypothesis  of  the  epigenic  or  pseudo- 
morphous  production  of  mineral  species,  which  underlies  the 
plutonists'  theory  of  metamorphosis  or  metasomatosis,  Delesse 
uses  the  following  language  :  "  Metamorphoses  the  most  im- 
probable, and  in  any  case  the  least  proved,  have  been  admitted 
by  a  whole  school  of  mineralogists.  It  is  thus,  for  example, 
that  orthoclase  is  (by  them)  connected  on  the  one  hand  with 
a  volcanic  mineral,  leucite,  —  from  which  they  would  derive 
it,  —  and  on  the  other  with  potash-mica,  supposed  to  be  formed 
from  the  orthoclase.  "With  the  help  of  the  chemical  formulas 


PREFACE.  XXXI 

of  these  minerals  they  show  that  leucite  can  be  successively 
transformed  into  analcime,  orthoclase,  and  kaolin,  and  finally 
into  a  potash-mica.  Although  the  change  of  some  of  these 
minerals  may  take  place  in  certain  points,  —  especially  the 
change  of  orthoclase  into  kaolin,  —  no  one  has  ever  yet 
observed  the  gradual  and  complete  series  of  all  these  trans- 
formations in  any  given  locality,  and  they  are  entirely  hypo- 
thetical."* The  reader  may  compare  the  above  citations  from 
Delesse  with  the  language  of  the  author  on  pages  287  and 
324  -  326  of  this  volume. 

J.  D.  Dana,  who  in  1845,  1854,  and  1858,  gave  expression 
to  the  extreme  views  of  the  plutonist  school  as  to  the  origin 
of  crystalline  schists  by  pseudomorphism,  which  have  been 
cited  on  pages  319  and  320,  declared  in  1874  that  these  ex- 
tracts from  his  writings  "did  not  express  the  opinions  on 
metamorphism  which  he  had  held  for  the  past  twelve  years  " ; 
but  that  the  "  Manual  of  Geology,"  published  by  him  in  1863, 
"  is  to  be  taken  as  a  correct  expression  of  its  author's  views  on 
this  question."  t  The  definitions  of  the  Manual  on  this  impor- 
tant matter,  which  have  already  been  noticed  on  page  321 
of  this  volume,  although  leaving  much  to  be  desired,  permit 
the  conclusion  that  its  author  has  abandoned  his  former 
opinions  on  metamorphism. 

T.  S.  H. 

BOSTON,  February,  1878. 

*  Bull,  de  la  Soc.  Geol.  de  France,  3me  serie,  Vol.  III.  pp.  154-160. 
t  Proc.  Bost  Soc.  Nat  Hist,  Vol.  XVII.  p.  169  and  Vol.  XVIII.  p.  200. 


TABLE  OF  CONTENTS. 


THEORY  OF  IGNEOUS  BOCKS  AND  VOLCANOES  (1858). 

PAGE 

The  chemistry  of  a  cooling  incandescent  globe 1 

The  primitive  ocean  and  primitive  crystalline  rock       ....  2 

Origin  of  eruptive  rocks;  views  of  Bunsen,  Phillips,  and  Durocher  .        .  3 

Softening  of  crystalline  stratified  rocks 4 

Poulett  Scrope  and  Scheerer  on  aqueo-igneous  fusion        ....  5 

Daubre*e  and  the  author  on  the  origin  of  mineral  silicates     ...  6 

Views  as  to  the  condition  of  the  earth's  interior 7 

Existence  of  a  solid  anhydrous  nucleus  maintained       ....  7 

Intervention  of  sedimentary  rocks  in  volcanic  phenomena        ...  8 

Origin  of  the  volatile  products  of  volcanoes 8 

Sir  J.  F.  W.  Herschel  on  the  cause  of  volcanic  action       ....  9 

Its  relation  to  recent  sedimentary  deposits 9 

Note  on  the  decomposition  of  crystalline  rocks .10 

Note  on  the  deposition  of  clays 10 

II. 
ON  SOME  POINTS  IN  CHEMICAL  GEOLOGY  (1859). 

Ancient  and  modern  sea-waters  compared 11 

Origin  and  geological  importance  of  alkaline  carbonates       ...  12 

Different  relations  of  potash  and  soda 12 

Deposits  of  iron-oxide  as  evidences  of  organic  life         ....  13 

Deposits  of  alumina;  emery  and  bauxite;  their  origin     ....  13 

Supposed  aqueous  origin  of  basic  and  acidic  eruptive  rocks          .        .  14 

Babbage  and  Herschel  on  the  effects  of  internal  heat         ....  15 

Theory  of  volcanic  and  plutonic  phenomena 15 

Note  on  the  views  of  Keferstein 16 

Geological  distribution  of  volcanoes 17 

IIL 

THE   CHEMISTRY  OF  METAMORPHIC  ROCKS  (1863). 

Preface ;  objections  to  the  name  of  metamorphic  rocks     ....  18 

Probable  relations  between  the  age  and  constitution  of  crystalline  rocks  19 

Sub-aerial  and  sub-aqueous  decay  of  feldspars 20 


xxxiv  TABLE  OF  CONTENTS. 

Chemistry  of  alkaline  natural  waters 21 

Relations  of  the  soil  to  potash-salts  and  phosphates  .       .        .        .'       .22 

Origin  of  insoluble  metallic  sulphides 23 

Deoxidation  of  metals,  sulphur,  and  carbon  through  vegetation        .        .  23 

Twofold  origin  of  carbonates  of  lime  and  magnesia        ....  23 

The  two  types  of  igneous  rocks ;  their  sedimentary  origin         ...  24 

Rock-metamorphism  defined  and  distinguished  from  pseudomorphism  24 
Relation  of  alkaline  waters  to  crystalline  silicates      .        .        ...        .25 

Local  metamorphism ;  views  of  Daubr4e  and  Naumann        ...  26 

Progressive  change  in  silico-aluminous  sediments 27 

Chemical  relations  of  certain  mineral  silicates 28 

Various  series  of  crystalline  stratified  rocks       .        .        .        .  .29 

Laurentian,  Labrador,  Green  Mountain,  and  White  Mountain  series    .  30 

The  hypothetical  granitic  substratum ;  granitic  veins        ....  33 

Crystalline  rocks  of  Europe  and  North  America  compared    ...  34 

IV. 

THE  CHEMISTRY  OF  THE  PRIMEVAL  EARTH  (1867). 

The  spectroscope  and  the  nebular  hypothesis 35 

Dissociation  defined ;  terrestrial  chemical  elements       ....  37 

Probable  existence  of  more  elemental  forms  of  matter  in  the  stars    .        .  37 

Chemical  and  physical  constitution  of  the  sun       .....  37 

Chemical  history  of  the  cooling  earth 38 

Probable  solidification  f^pm  the  centre 39 

Primitive  atmosphere  and  ocean ;  their  composition 40 

Their  action  on  the  primitive  crust 40 

Mutual  relations  of  carbonic  acid,  clay,  limestone,  and  sea-salt        .        .  41 

Waters  of  the  ancient  ocean 41 

Carbonic  acid  of  the  ancient  atmosphere    .......  42 

Its  relations  to  life  and  to  climate 42 

Formation  of  gypsums  and  magnesian  limestones      .        .        .  .43 

Secondary  and  aqueous  origin  of  granites      ......  43 

Action  of  internal  heat ;  volcanoes 44 

Hopkins,  Pratt,  and  Sir  William  Thomson  on  the  earth's  interior        .  45 

Controversies  of  the  neptunists  and  plutonists 45 

APPENDIX. 

The  earth's  climate  in  former  ages 46 

Tyndall  on  the  relation  of  gases  and  vapors  to  radiant  heat  ...  46 

Former  predominance  of  carbonic  acid  in  the  air 47 

Note  on  the  amount  of  carbonic  acid  now  fixed  in  limestones        .        .  47 


y. 

THE  ORIGIN  OF  MOUNTAINS  (1861). 

Hall  on  palaeozoic  sediments  in  eastern  North  America     ....      49 
Eastern  origin  of  these  mechanical  sediments 49 


TABLE  OF  CONTENTS.  XXXV 

Varying  thickness  of  pakeozoic  strata 60 

Relation  of  mountains  to  sedimentation 50 

Continental  as  opposed  to  local  elevation 52 

Views  of  Buffon,  Montlosier,  and  Constant-Prevost        ....  52 

Views  of  Humboldt,  Von  Buch,  and  Elie  de  Beaumont     ....  62 

Lesley  on  the  topography  of  mountains 52 

Relations  of  mountains  to  synclinals  and  to  erosion 52 

Hall's  views  of  the  origin  of  mountains 54 

Relations  of  subsidence  to  foldings  of  strata 55 

Condensation  consequent  on  the  crystallizing  of  sediments   ...  56 

The  hypothesis  of  a  solid  contracting  nucleus  maintained         ...  57 

Relation  of  this  nucleus  to  water-impregnated  sediments       ...  57 

The  softening  of  these  produces  lines  of  weakness  in  the  crust ...  57 

Relation  of  this  process  to  corrugations 57 

Relations  of  volcanic  and  plutonic  phenomena  to  sedimentation       .       .  58 

VI. 

• 

THE  PROBABLE  SEAT  OF  VOLCANIC  ACTION  (1869). 

Discussion  of  the  views  of  Hopkins  and  Scrope  on  volcanoes     ...  59 

Views  of  Lemery  and  Breislak,  of  Davy  and  Daubeny          ...  62 

Views  of  Keferstein  and  Sir  J.  F.  W.  Herschel 62 

Exposition  of  the  author's  view      ........  63 

Disintegration  of  the  primitive  crust 63 

Hopkins  on  internal  heat  and  its  increase  in  descending        ...  64 

Sorby  on  the  relations  of  heat  and  pressure  to  fusion  and  solution    .        .  65 

Chemical  differences  in  eruptive  rocks 66 

APPENDIX. 

Geographical  distribution  of  modern  volcanoes 68 

Distribution  of  ancient  eruptive  rocks ;  their  geological  relations  .        .  69 

VII. 

ON  SOME  POINTS  IN  DYNAMICAL  GEOLOGY  (1858). 

LeConte  on  the  reconstruction  of  geological  theory TO 

His  views  compared  with  those  of  the  author 71 

Hall's  theory  of  mountains ;  the  criticisms  of  Dana,  Whitney,  and  LeConte  73 

Views  of  Hall  and  the  author  misunderstood 

LeConte's  theory  of  mountains  considered 74 

Continental  elevation  and  erosion;  Montlosier  and  Jukes 

Hall  on  some  North  American  mountains  .....••  75 

Origin  and  structure  of  the  Appalachians   ' 76 

Their  crystalline  strata  not  palaeozoic  but  eozic                                   •        •  75 

Evidences  of  an  eastern  pre  palaeozoic  continent 75 

Dry  climate  of  eastern  North  America  in  palaeozoic  times         ...  76 

Oscillations  of  continents;  their  cause 76 


xxxvi  TABLE  OF  CONTENTS. 

Source  of  heat  in  plutonic  phenomena 77 

The  notion  of  its  chemical  origin  untenable 77 

Henry  Wurtz  on  a  mechanical  source  of  heat 78 

Experiments  and  conclusions  of  Mallet ,  78 

His  views  on  the  origin  of  volcanic  products 79 

VIII. 

ON  LIMESTONES,  DOLOMITES,  AND  GYPSUMS  (1858-1866). 

Introductory  note;  letter  to  Eliede  Beaumont 80 

Cordier's  views  of  the  origin  of  limestones  and  dolomites      ...  81 

Their  identity  with  those  of  the  author 82 

Chemistry  of  evaporating  lakes  and  sea-basins 83 

Alkaline  waters  of  rivers  and  springs 84 

Separation  of  lime-salts  from  sea-water:  gypsum  and  rock-salt    .        .  85 

Origin  of  sulphuretted  hydrogen  and  native  sulphur          ....  87 

Origin  of  deposits  of  magnesian  limestones 88 

Their  deposition  necessarily  in  isolated  basins  .        .        .        .  88 

Hall  on  the  organic  remains  in  magnesian  limestones    ....  88 

Deposits  of  pure  carbonate  of  lime 89 

Generation  of  dolomite ;  its  crystallization 89 

Note  on  chemically  deposited  silica 89 

Conclusions  as  to  the  chemistry  of  gypsum  and  dolomite      ...  90 

Conditions  of  temperature  for  the  production  of  dolomite  ....  91 

Relative  solubilities  of  gypsum  and  magnesian  bicarbonate           .        .  91 

Influence  of  carbonic  acid  on  the  formation  of  gypsum      ....  91 

Geographical  and  climatic  conditions  for  the  production  of  dolomite    .  91 

Recent  conclusions  of  Ramsay  as  to  magnesian  limestones        ...  92 

IX. 

THE  CHEMISTRY  OF  NATURAL  WATERS. 

PART  I.  —  GENERAL  PRINCIPLES. 

Atmospheric  waters  and  the  result  of  vegetable  decay  ....  94 

Action  of  waters  on  the  soil;  researches  of  Way  and  Voelcker         .        .  95 

Eichhorn  on  the  replacement  of  protoxide  bases  in  silicates  .        .        .  96 

Possible  relations  of  saline  waters  to  the  soil 97 

Relations  of  organic  matters  to  oxides  of  iron  and  manganese       .        .  98 

Solution  and  deposition  of  alumina 98 

Origin  of  sulphuretted  hydrogen  and  sulphurets 99 

Decomposition  of  silicates;  studies  of  Ebelmann 100 

Kaolinization  of  feldspars  and  other  minerals 101 

Relation  of  soda  and  potash  salts  to  sediments  ......  101 

Carbonic  acid  and  water  as  agents  in  decomposing  rocks     .        .        .  102 

Marine  salts  in  solution  in  sedimentary  strata 103 

Porous  nature  of  sandstones  and  dolomites 103 

Calculations  as  to  the  volume  of  waters  held  in  rocky  strata     .        .        .  104 

Solid  salts  and  bitterns  from  sea-water  in  the  rock's       ....  105 


TABLE  OF  CONTENTS.  xxxvu 

Action  of  bicarbonate  of  soda  on  calcareous  and  magnesian  salts      .       .  105 

Origin  of  sulphates  in  natural  waters 106 

Indifference  of  gypsum  solutions  to  dolomite 106 

Decomposition  of  gypsum  by  hydrous  magnesian  carbonate         .        .  107 

Results  of  the  gradual  evaporation  of  sea-water 107 

Composition  of  the  ancient  seas 108 

Separation  of  the  lime  salts  from  sea-water 109 

Decomposition  of  sulphate  of  magnesia  by  bicarbonate  of  lime     .        .  109 

Twofold  origin  of  gypsum 110 

Twofold  origin  of  magnesian  carbonate 110 

Sulphuric  and  hydrochloric  acid  in  waters Ill 

Carbonic  acid  in  waters .        .        .        , .    .. 112 

Ammonia  and  nitrogen  in  rocks  and  waters 113 

Classification  of  natural  waters 113 

PART  II.  —  ANALYSES  OF  VARIOUS  NATURAL  WATERS. 

Waters  of  the  first  class  or  bitter  salines ;  analyses 116 

Their  resemblance  to  bitterns ;  absence  of  sulphates     ....  117 

Predominance  of  chlorides  of  calcium  and  magnesium       ....  118 

Probable  constitution  of  the  Cambrian  ocean         .....  119 

Brines  of  ancient  saliferous  deposits 119 

Note  on  analyses  of  saline  waters 120 

Silicate  of  magnesia;  its  formation  and  chemical  relations        .        .        .  122 

Waters  of  the  second  and  third  classes;  analyses 123 

Waters  of  the  fourth  class  or  alkaline  waters ;  analyses     ....  125 

Waters  of  the  Ottawa  Eiver;  analysis 126 

Variations  in  the  composition  of  mineral  springs 127 

Comparative  analyses  of  the  Caledonia  waters 129 

Sulphuric-acid  springs  of  New  York  and  Ontario 130 

Neutral  sulphated  waters ;  their  sources 132 

Sulphate  of  magnesia  in  waters 134 

PART  III.  —  CHEMICAL  AND  GEOLOGICAL  CONSIDERATIONS. 

Salts  of  the  alkaline  metals  in  natural  waters 135 

Salts  of  calcium  and  magnesium;  relations  of  chlorides  and  carbonates  .  137 

Results  of  evaporation ;  deposition  of  carbonates  of  lime  and  magnesia  138 

Solubility  of  carbonate  and  bicarbonate  of  lime 139 

Supersaturated  solutions  of  carbonates  of  lime  and  magnesia        .        .  140 

Salts  of  barium  and  strontium  in  waters 141 

Iron,  manganese,  alumina,  and  phosphates  in  waters    ....  142 

Bromides  and  iodides  in  waters 142 

Relations  of  chlorides  and  iodides  to  earthy  minerals    ....  143 

Sulphates  in  natural  waters ;  their  frequent  absence          ....  144 

Soluble  sulphides  in  natural  waters 145 

Borates;  waters  of  a  borax-lake 146 

Carbonates ;  studies  of  the  Caledonia  waters 147 

Waters  with  a  deficiency  of  carbonic  acid 149 

Silica ;  its  amount  in  various  waters 150 

Silicates  of  lime  and  magnesia  deposited  from  waters       .        .        .        .151 


XXXVlll  TABLE  OF   CONTENTS. 

Organic  matters  in  water ;  their  nature  and  origin         ....  152 

Geological  relations  of  mineral  waters 153 

Palaeozoic  formations  of  the  St.  Lawrence  basin     .....  154 

Kelations  of  mineral  waters  to  the  various  formations        ....  156 

Contiguity  of  dissimilar  mineral  springs 157 

Temperatures  of  the  mineral  waters  of  Canada  ......  157 

Results  of  the  evaporation  of  these  waters ,  158 

SUPPLEMENT. 

Waters  with  a  predominance  of  chloride  of  calcium  .        .        .        .        .  158 

Waters  with  soluble  sulphides ;  mode  of  analysis 159 

APPENDIX. 

On  the  porosity  of  rocks  and  its  significance 164 

Mode  of  determining  the  density  and  porosity  of  rocks  ....  165 

Table  of  the  density  and  porosity  of  various  rocks 166 

X. 

ON  PETROLEUM,  ASPHALT,  PYROSCHISTS,  AND  COAL. 

Geological  relations  of  petroleum        ........  168 

Origin  and  source  of  petroleum 170 

The  oil-bearing  limestone  of  Chicago;  its  analysis 172 

Large  amount  of  petroleum  contained  in  the  limestone  ....  173 

Bitumens ;  their  analyses  and  chemical  composition 175 

Wall  on  the  bitumens  of  Trinidad  and  Venezuela 176 

Convei-sion  of  organic  matters  into  coals  and  bitumen       ....  177 

Pyroschists  or  bituminous  shales;  their  nature  denned         .        .        .  177 

Their  geological  and  chemical  relations 178 

Chemical  similarity  of  animal  and  vegetable  tissues      ....  179 

Note  on  the  constitution  and  artificial  production  of  albuminoids     .        .  180 

Dawson  on  the  origin  of  coal  .........  181 

Comparative  analyses  of  epidermal  tissues 181 

On  the  gaseous  hydrocarbons  found  in  nature 182 

XI. 

ON  GRANITES  AND  GRANITIC  VEIN-STONES  (1871-1872). 

Granite  and  its  varieties  defined 184 

The  relations  of  granite  to  gneiss    ........  185 

Stratiform  structure  in  various  erupted  rocks 186 

Feldspar-porphyries ;  their  characters  and  distribution          .        .        .  187 

Granitoid  gneisses  of  New  England;  true  granites      .....  188 

Granitic  vein -stones;  theories  as  to  their  origin 189 

Views  of  Scheerer,  Scrope,  and  Elie  de  Beaumont     .        .        .        .        .189 

The  concretionary  origin  of  granitic  veins 192 

Granitic  vein-stones  of  the  White  Mountain  rocks  described      .        .        .  194 

Their  banded  structure;  disturbance  of  the  strata  by  veins  .        .        .  196 


TABLE  OF  CONTENTS.  xxxix 

Evidences  of  the  progressive  formation  of  such  veins     """.       .       .        .198 

Rare  minerals  in  the  granitic  vein-stones  of  New  England    .        .        .  200 

Geodes  in  granites  in  New  Brunswick  and  Italy 201 

Granitic  veins  distinguished  from  dikes         •     .  •  »              .        .        .  202 

Volger  and  Fournet  on  the  filling  of  granite  veins 202 

Recent  age  of  some  concretionary  veins 203 

Note  on  the  salt-wells  of  Goderich  in  Ontario 204 

On  the  conditions  of  the  crystallization  of  quartz 205 

On  the  emerald-bearing  veins  of  New  Grenada 205 

Recent  production  of  crystalline  zeolites 205 

The  Laurentian  series ;  its  lithological  characters 206 

Vein-stones  in  the  Laurentian  rocks 208 

These  vein-stones  compared  with  those  of  Scandinavia      ....  209 

Minerals  of  the  Laurentian  vein-stones 210 

Note  on  the  occurrence  of  leucite 210 

The  concretionary  character  of  these  vein-stones  shown        .        .        .  211 

Incrustation  and  skeleton-crystals  described 2U 

Crystals  with  rounded  angles ;  their  significance 212 

Feldspathic  veins  of  the  Laurentian  rocks 214 

Complex  nature  of  the  Laurentian  vein-stones 215 

Vein-stones  with  apatite  and  with  graphite        .        .        .        .        .        .  216 

Paragenesis  of  their  mineral  species 216 

Concretionary  copper-bearing  veins  of  the  Blue  Ridge       ....  217 

Supposed  eruptive  origin  of  crystalline  limestones         ....  218 

XII. 

THE  ORIGIN  OF  METALLIFEROUS  DEPOSITS. 

Preliminary  statement  of  the  theory  of  ore-deposits  .....  220 

Distribution  and  diffusion  of  the  chemical  elements       ....  221 

Separation  and  concentration  of  certain  elements 222 

Note  on  the  solvent  powers  of  water 223 

The  terrestrial  circulation  compared  with  that  of  animals         .        .        .  224 

History  of  the  diffusion  and  concentration  of  phosphates       .        .        .  225 

Potash  and  iodine ;  their  elimination  from  sea-water         ....  226 

Intervention  of  organic  life  in  all  these  processes 226 

History  of  the  diffusion  and  the  concentration  of  iron        ....  227 

Relation  of  iron-oxides  to  ancient  vegetation  ......  229 

Formation  of  iron-pyrites  and  other  sulphides 230 

Diffusion  of  copper,  silver,  and  lead  in  the  ocean 231 

Reduction  of  copper  from  its  solutions 232 

Ore-deposits  in  beds  and  hi  fissures 233 

The  process  of  deposition  in  veins 234 

Uniformity  of  operations  in  nature 235 

APPEXDIX. 

Sonstadt  on  the  iodine  in  sea-water 237 

On  gold  in  the  rcean ;  Sonstadt  and  Henry  Wurtz         ....  237 


xl  TABLE   OF  CONTENTS. 

XIII. 

THE  GEOGNOSY  OF  THE  APPALACHIANS  AND  THE  ORIGIN  OF 
CRYSTALLINE  ROCKS. 

The  relations  of  geology  to  the  sciences 240 

PART  I.  —THE  GEOGNOSY  OF  THE  APPALACHIAN  SYSTEM. 

History  of  the  Appalachian  mountain  system 241 

Eaton  on  the  classification  of  rock-formations 241 

Jackson  and  Rogers  on  the  rocks  of  New  England        ....  242 

The  Adirondack  or  Laurentide  series ;  Laurentian 243 

The  Green  Mountain  series ;  Huronian •  243 

The  White  Mountain  series ;  Montalban 244 

Rogers  on  the  crystalline  rocks  of  Pennsylvania 245 

His  hypozoic  and  azoic  series  probably  identical 247 

Crystalline  rocks  of  New  York  and  New  England          ....  248 

Crystalline  rocks  of  Virginia,  the  Carolinas,  and  Tennessee      .        .        .  249 

Emmons  on  the  crystalline  rocks  of  western  New  England    ...  250 

Note  on  the  decay  of  these  rocks  to  the  southwest 250 

The  Taconic  rocks  of  Emmons  distinguished  from  the  primary    .        .  251 

The  Taconic  system  described  and  defined 252 

Views  of  Mather  and  Rogers  on  the  Taconic  rocks        ....  254 

Rogers  and  Safford  on  the  primal  rocks  of  Virginia  and  Tennessee  .        .  255 

Relations  of  the  Taconic  to  the  Champlain  division        ....  256 
The  organic  remains  of  the  Taconic  rocks .        .        .        .        .        .        .257 

The  rocks  of  the  so-called  Quebec  group 259 

The  Red  sand-rock  of  western  Vermont 260 

Lower  palaeozoic  rocks  of  Labrador  and  Newfoundland         .        .        .  261 

Lower  palaeozoic  rocks  in  the  Champlain  and  Mississippi  valleys     .        .  261 

Note  on  the  palaeozoic  formations  in  the  Rocky  Mountains   .        .        .  262 

Stratigraphical  breaks  in  the  lower  palaeozoic  series 263 

Continuation  of  the  Taconic  controversy 264 

The  Upper  and  Lower  Potsdam  of  Billings 266 

Lower  palaeozoic  rocks  of  Europe 266 

Identity  of  Taconic  with  Lower  and  Middle  Cambrian       .        .        .        .268 

The  Huronian  or  Urschiefer  distinct  from  Cambrian     ....  269 

Crystalline  schists  of  Anglesea  and  the  Rhine 270 

Crystalline  rocks  of  the  Scotch  Highlands 271 

Comparative  studies  of  crystalline  formations    .        .        •        •        .  272 

Crystalline  schists  of  Lakes  Huron  and  Superior 274 

The  crystalline  schists  of  the  Appalachians,  pre-Cambrian       .        .        .  276 

Credner  on  the  Eozoic  formations  of  North  America      ....  277 

History  of  the  Norian  or  Labrador  rocks 279 

Relations  of  the  various  crystalline  formations       .....  281 

Hitchcock  on  the  geology  of  the  White  Mountains 282 

PART  II.  —  THE  ORIGIN  OF  CRYSTALLINE  ROCKS. 

Mineralogy  of  the  two  classes  of  crystalline  rocks          .        .        .        •  283 

Theories  of  the  source  of  eruptive  rocks 284 


TABLE   OF   CONTENTS.  xli 

Mechanical  disintegration  and  recomposition  of  rocks   ....  285 

Crystalline  silicated  rocks  of  stratified  formations 286 

Two  hypotheses  to  explain  their  origin 286 

Alleged  pseudomorphous  change  of  plutonic  rocks 286 

The  doctrine  of  pseudomorphism  by  alteration 287 

Symmetrical  and  asymmetrical  envelopment  of  minerals  ....  288 

Difficulties  of  the  doctrine  of  pseudomorphous  alteration       .        .        .  290 

Scheerer's  doctrine  of  polymeric  isomorphism 291 

Delesse  and  Naumann  on  pseudomorphism    ......  292 

Supposed  plutonic  origin  of  crystalline  stratified  rocks      ....  294 

Views  of  Naumann  and  of  Macfarlane  on  primary  rocks       .        .        .  294 

Hypothesis  of  the  aqueous  origin  of  crystalline  rocks         ....  296 

Generation  of  silicates  in  cases  of  local  alteration 297 

Aqueous  deposition  of  feldspathic  minerals         ......  298 

Alleged  palaeozoic  age  of  many  crystalline  schists          ....  299 

The  author's  view  of  their  origin  defined 300 

Early  views  of  the  aqueous  origin  of  crystalline  rocks   ....  301 

Evidences  of  life  at  the  time  of  their  deposition 301 

Evidences  of  life  afforded  by  meteoric  stones ......  302 

Discovery  of  the  Eozoon  Canadense 302 

Silicates  injecting  this  and  various  other  organisms       ....  303 

Observations  of  Giimbel,  Hoffmann,  and  Dawson 303 

Credner  and  Giimbel  on  the  origin  of  crystalline  schists        .        .        .  304 

Giimbel  on  diagenesis  and  epigenesis          .......  305 

Note  containing  the  views  of  Giimbel  on  this  question  ....  305 

Note  on  the  crystalline  aggregation  of  finely  divided  matter      .        .        .305 

Conditions  of  early  times  favoring  diagenesis 306 

The  origin  and  formation  of  dolomites 307 

Influence  of  carbonic  acid  on  the  production  of  dolomite       .        .        .  308 

Supposed  generation  of  dolomite  by  Von  Morlot  and  Marignac          .        .  308 

Two  classes  of  dolomites ;  their  origin 310 

Relations  of  one  class  of  these  to  gypsum  and  rock-salt     ....  310 

Former  climate  of  eastern  North  America 310 

Magnesian  silicates  of  Syracuse,  New  York 310 

Supposed  organic  origin  of  limestones 311 

Their  true  relation  to  organic  life 311 

Relations  of  phosphates  to  organisms 311 

Phosphatic  nature  of  Lingula,  Orbicula,  Conularia,  etc 312 

Relations  of  silica  to  organic  life 312 

APPENDIX. 

Reply  to  Mr.  Dana's  criticisms 313 

The  question  of  the  transmutation  of  species  stated        ....  313 

Warrington  Smyth's  opinion  of  epigenesis 313 

The  views  of  Delesse  on  pseudomorphism  defined          ....  314 

Delesse  on  the  eruptive  origin  of  serpentine 316 

He  subsequently  adopts  the  view  of  its  aqueous  origin  ....  317 

A  revolution  in  the  theory  of  crystalline  rocks 317 

Scheerer's  views  explained  and  defended 318 


xlii  TABLE  OF  CONTENTS. 

Dana's  teachings  as  to  pseudomorphism '               .  319 

He  affirms  the  doctrine  of  epigenic  metamorphism         ....  320 
The  old  doctrine  of  diagenesis  explained  and  defended      .        .        .        .321 

The  views  of  Naumann  examined 322 

Various  illustrations  of  the  doctrine  of  transmutation        ....  324 

King  and  Rowney  on  the  supposed  transformations  of  serpentine          .  325 

Genth  on  the.supposed  alterations  of  corundum 326 

Dana  and  Emmons  on  the  Taconic  rocks 326 

On  the  relations  of  the  pre-Cambrian  schists 327 


XIV. 

THE  GEOLOGY  OF  THE  ALPS. 

The  researches  of  Alphonse  Favre 328 

The  crystalline  rocks  of  Mont  Blanc 329 

The  uncrystalline  rocks  around  it 331 

Association  of  carboniferous  and  liassic  fossils       .....  332 

Difficulties  presented  by  folded  and  inverted  strata 334 

Sismonda  on  the  anthracitic  system  of  the  Alps 334 

Section  presented  by  the  Mont  Cenis  Tunnel 335 

Age  of  the  crystalline  schists  with  anhydrites 336 

Examples  of  inverted  strata  in  the  Alps 337 

On  the  supposed  recent  age  of  the  crystalline  schists     ....  338 

The  recomposed  crystalline  rocks  of  the  Alps 339 

The  true  crystalline  schists  of  great  antiquity 341 

Little  or  no  evidence  of  metamorphism  in  the  Alps    .....  342 

The  fan-like  structure  of  the  Alps  explained 343 

Grand  section  across  Chamonix  and  Mont  Blanc 343 

Geological  history  of  Mont  Blanc    ........  344 

APPENDIX. 

Antiquity  of  the  crystalline  schists  of  Mont  Cenis 347 

Favre  on  the  origin  of  crystalline  schists 347 

De  Beaumont  and  Fillet  on  the  rocks  of  Mont  Cenis  Tunnel      .        .        .348 


XV. 

HISTORY  OF  THE  NAMES  CAMBRIAN  AND  SILURIAN  IN  GEOLOGY. 
PART  I.  —  SILURIAN  AND  UPPER  CAMBRIAN  IN  GREAT  BRITAIN. 

The  Gray  wacke  formation  of  the  older  geologists 350 

Early  studies  of  Sedgwick  in  North  Wales 350 

Early  researches  of  Murchison  in  Wales         ......  351 

Cambrian  as  first  defined  by  Sedgwick 352 

Silurian  as  first  defined  by  Murchison 353 

Examination  of  the  Berwyns  by  Murchison  and  Sedgwick        .        .        .  354 

Identity  of  Cambrian  and  Lower  Silurian  fossils 355 


TABLE  OF  CONTENTS.  xliii 

Publication  of  Murchison's  Silurian  System      .        .        ...        .  856 

Difficulty  of  distinguishing  between  Cambrian  and  Silurian  .        .        .  355 

Sedgwick's  views  and  position  misrepresented  .        .        .        .        .        .  357 

Errors  of  Murchison's  sections  exposed  .        ......  358 

His  Silurian  system  based  upon  a  series  of  mistakes  .        .       .        .        .  362 

Sedgwick's  proposed  compromise  in  nomenclature        ....  363 

Unauthorized  alteration  of  Sedgwick's  geological  map      .        .        .        .  364 

Further  history  of  Sedgwick's  wrongs 364 

PART  II.  —  MIDDLE  AND  LOWER  CAMBRIAN. 

Ancient  fossiliferous  rocks  of  Scandinavia         , 365 

The  early  studies  of  Hisinger  ;  curious  errors 366 

Section  of  the  rocks  of  Kinnekulle      ........  367 

Angelin  on  the  Crustacea  of  Scandinavia       .        . '     •'  «•  .     .        .        .  367 

Barrande  on  the  fossiliferous  rocks  of  Bohemia 368 

The  so-called  primordial  Silurian   .        .' 369 

The  fossils  of  the  Lingula  flags  of  Wales 370 

Fossiliferous  rocks  of  the  Malvern  Hills          ......  370 

Subdivision  of  the  Lingula  flags  ;  the  Menevian  beds        ....  371 

Fossils  of  Lower  Cambrian  or  Harlech  rocks 372 

True  boundary  between  Cambrian  and  Silurian 374 

Breaks  in  the  succession  of  the  lower  rocks 375 

Note  on  the  Tremadoc  rocks 375 

Ramsay  on  stratigraphical  breaks 376 

General  considerations  on  breaks  in  geological  series         ....  377 

Note  on  the  thickness  of  British  Cambrian  and  Silurian         .        .        .  377 

Murchison  and  the  Cambrian  nomenclature 378 

He  confounds  the  Longmynd  and  Bala  groups 380 

The  statements  of  his  Siluria  criticised       ..      .     • 380 

Disagreement  as  to  the  Cambrian  and  Silurian  nomenclature       .        .  381 

Distribution  of  Lower  and  Middle  Cambrian  rocks 382 

Crystalline  schists  of  Malvern  and  of  Anglesea 383 

Gold-bearing  Lingula  flags  of  North  Wales 383 

Hicks  on  the  classification  of  lower  palaeozoic  rocks      ....  384 

Sedgwick's  latest  views  on  classification    ...;...  884 

Tabular  view  of  lower  palaeozoic  rocks 386 

PART  m.  — CAMBRIAN  AND  SILURIAN  ROCKS  IN  NORTH  AMERICA. 

The  geological  survey  of  New  York 387 

Hall  on  the  rocks  of  the  New  York  system            *  387 

The  Taconic  system  equivalent  to  Lower  and  Middle  Cambrian        .        .  388 

The  paleontological  determinations  of  Hall     ....        .        .        .  389 

Stratigraphical  errors  of  the  Taconic  system      .        .        .        ...        .  390 

The  Red  sand-rock  and  the  primordial  trilobites  of  Vermont         .        .  391 
Contributions  of  Barrande  and  Billings  to  the  subject       .        .        .        .392 

Logan  on  the  Taconic  rocks  of  Vermont 394 

Hall's  determinations  and  the  errors  of  Hisinger 396 

Bigsby  on  the  fossiliferous  rocks  near  Quebec 396 

Bayfield  and  Logan  on  the  same  rocks 397 


xliv  TABLE  OF  CONTENTS. 

The  graptolites  of  Point  Levis 399 

Discovery  of  trilobites  at  Point  Levis 400 

Logan  describes  and  defines  the  Quebec  group 401 

He  supposes  a  great  and  continuous  dislocation 402 

Hall  accepts  Logan's  stratigraphical  conclusions 403 

Potsdam  of  the  Ottawa  basin  and  of  Wisconsin 403 

Its  relations  to  the  primordial  of  Europe 404 

History  of  the  Paradoxides  Harlani  of  Braintree 405 

The  primordial  fauna  in  Newfoundland  and  New  Brunswick        .        .  406 

Murray  on  the  geology  of  Newfoundland 406 

The  Lower  Potsdam  fauna  of  Billings 407 

Fossiliferous  rocks  of  Troy,  New  York 407 

Menevian  fauna  in  New  Brunswick 407 

Crystalline  schists  of  Nova  Scotia 408 

Eophyton  and  its  supposed  geological  relations 409 

Hicks  and  Barrande  on  the  early  trilobitic  fauna 409 

Murray  on  ancient  fossiliferous  rocks  in  Newfoundland         .        .        .  410 

Dawson  on  ancient  foraminiferal  forms 411 

On  the  Palgeotrochis  of  Emmons 411 

Billings  on  paleontological  breaks  in  the  Ottawa  basin       ....  412 

The  true  horizon  of  the  Levis  limestone 412 

Its  equivalents  in  Great  Britain  and  elsewhere  ......  412 

Unconformability  of  Calciferous  and  Trenton  formations      .        .        .  413 

Discordance  between  the  Quebec  and  Trenton  groups        ....  413 

Lesley  on  a  similar  discordance  in  Pennsylvania 414 

The  Chazy  formation  on  the  Ottawa  River 414 

Absence  of  the  second  fauna  to  the  eastward 415 

Distribution  of  the  Lower  Helderberg  fauna       .        .        .        .        .        .  415 

History  of  the  Oneida  conglomerate 416 

Mingling  of  second  and  third  faunas  on  the  Saguenay        ....  417 

Fossiliferous  rocks  of  Anticosti 417 

Middle  Silurian  division  in  Great  Britain 417 

Middle  Silurian  of  Billings  different  therefrom 418 

Two  faunas  in  the  Upper  Silurian  of  Murchison 418 

The  Onondaga  and  Water-lime  formations 418 

Introduction  of  the  terms  Silurian  and  Devonian  in  America     .        .        .  419 

Views  of  De  Verneuil  and  of  Hall 419 

Names  adopted  by  the  geological  survey  of  Canada 420 

The  geological  survey  of  Pennsylvania 420 

The  nomenclature  adopted  by  Rogers 421 

Rogers  on  the  British  equivalents  of  American  rocks     ....  422 

Errors  of  the  Silurian  nomenclature 422 

The  Upper  Cambrian  or  Siluro-Cambrian  division         ....  423 

Jukes  and  Giekie  on  the  Silurian  nomenclature 424 

Barrande's  downward  extension  of  Silurian 424 

Great  importance  of  Sedgwick's  geological  labors 425 


TABLE  OF  CONTENTS.  xlv 

XVI. 

THEORY  OF  CHEMICAL  CHANGES  AND  EQUIVALENT  VOLUMES 

(1853). 

The  physical  and  chemical  history  of  matter 426 

Generation  of  chemical  species  considered 427 

Theory  of  double  decomposition 428 

On  the  relations  of  lower  to  higher  species 428 

The  significance  of  combination  by  volumes 429 

The  nature  of  chemical  union  and  of  solution 429 

Relations  of  chlorine  to  hydrogen  and  hydrocarbons      ....  430 

Laurent's  law  of  divisibility  in  formulas 431 

Reasons  for  doubling  the  equivalents  of  oxygen  and  carbon  .        .        .  431 

Extension  of  the  principle  of  progressive  series 432 

Relations  between  density  and  equivalent  weight  in  gases     .        .        .  432 
Relations  between  density  and  equivalent  weight  in  solids        .        .        .433 

High  equivalent  weights  of  solid  species 434 

Playfair  and  Joule  on  equivalent  volumes 434 

Equivalent  volumes  of  crystalline  solids 435 

Equivalent  volumes  of  liquid  species 436 

xvii. 

THE  CONSTITUTION  AND   EQUIVALENT   VOLUME   OF   MINERAL 
SPECIES  (1853-1863). 

Progressive  or  homologous  series  hi  chemistry 439 

General  formula  for  silica  and  other  oxides 440 

Equivalent  volume  of  certain  salts 440 

Probable  constitution  of  the  carbon-spars 441 

Illustrations  of  isomorphism  and  of  homology 442 

Relations  between  the  various  triclinic  feldspars 443 

A  similar  view  subsequently  adopted  by  Tschennak     ....  444 

The  feldspathides ;  scapolites,  beryl,  and  iolite 445 

The  grenatides ;  zoisite  or  sanssurite •  446 

Polymerism  in  mineral  species  illustrated 446 

Relations  between  the  jades  and  the  scapolites 447 

The  allomerism  of  Professor  Cooke 447 

XVIIL 

THOUGHTS  ON  SOLUTION  AND  THE  CHEMICAL  PROCESS  (1854). 

Views  of  various  chemists  as  to  the  nature  of  solution  .        ...  448 

Solution  maintained  to  be  chemical  union 449 

Chemical  union  is  identification 450 

Chemical  decomposition  or  differentiation 451 

Nature  of  double  decomposition 451 

Action  by  pressure  or  catalysis 452 


xlvi  TABLE  OF  CONTENTS. 


XIX. 

ON  THE  OBJECTS  AND  METHOD  OF  MINERALOGY  (1867). 

Mineralogy  in  its  relations  to  chemistry  and  natural  history  .        .        .  453 

Mineralogy  the  natural  history  of  all  unorganized  matter  ....  454 

Objects  to  be  attained  in  a  natural  classification 454 

Views  of  Oken  and  of  Stallo 454 

The  nature  of  chemical  species  defined 455 

Varying  condensation  and  equivalents  of  solid  species       ....  455 

Relations  of  vapors  to  liquids  and  solids 456 

Evidences  of  polymerism  in  solid  species 457 


THEORY  OF  TYPES  IN  CHEMISTRY  (1848-1861). 

Kolbe  on  oxides  of  carbon  as  types  in  chemistry        ...        .        .        .  459 

Ad.  Wurtz's  criticism  of  Kolbe 460 

Importance  of  the  conception  of  types  in  chemistry   .        .        .        .  •     .  461 

Views  of  Williamson  and  of  Gerhardt 462 

Laurent  on  water  as  a  type 463 

The  author's  views  on  the  water-type' 463 

On  anhydrous  monobasic  acids 464 

The  conception  of  condensed  or  polymeric  types 464 

The  nature  of  sulphur,  ozone,  and  nitrogen 464 

Hydrogen  the  fundamental  type     ........  465 

Note  on  the  theory  of  nitrification 465 

On  the  value  and  significance  of  rational  formulas         ....  465 

The  hypothesis  of  radicles  and  substitution  by  residues    ....  465 

Ad.  Wurtz  on  polyatomic  radicles 466 

The  genesis  of  the  phosphoric  acids  explained  ......  466 

Gerhardt  on  polybasic  and  sub-salts       .......  467 

The  sulphates  considered  as  derived  from  polyatomic  radicles  .        .        .  467 

Priority  of  the  author  to  Williamson  and  to  Gerhardt    .        .        .        .  468 

APPENDIX. 

The  theory  of  nitrification 470 

Views  as  to  the  double  nature  of  nitrogen  gas 470 

Its  conversion  into  ammonia  and  nitrous  acid 470 

The  intervention  of  ozone  in  the  process 471 

Experiments  of  Schb'nbein  on  nitrification 471 

Nickles  on  the  priority  of  the  author 472 

Schaefler  on  the  theory  of  nitrification 473 


THEORY   OF   IGNEOUS    ROCKS    AND 
VOLCANOES. 

(1858.) 

The  following  Essay,  read  before  the  Canadian  Institute,  at  Toronto,  March  13,  1858, 
was  printed  in  the  Canadian  Journal  for  May  of  the  same  year.  It  may  be  regarded 
as  a  first  contribution  to  the  theoretical  notions  developed  in  some  of  the  following 
papers. 

IN  a  note  in  the  American  Journal  of  Science  for  January, 
1858,  I  have  ventured  to  put  forward  some  speculations  upon 
the  chemistry  of  a  cooling  globe,  such  as  the  igneous  theory 
supposes  our  earth  to  have  been  at  an  early  period.  Consid- 
ering only  the  crust  with  which  geology  makes  us  acquainted, 
and  the  liquid  and  gaseous  elements  which  now  surround  it, 
I  have  endeavored  to  show  that  we  may  attain  to  some  idea 
of  the  chemical  conditions  of  the  cooling  mass  by  conceiving 
these  materials  to  again  react  upon  each  other  under  the  influ- 
ence of  an  intense  heat.  The  quartz,  which  is  present  in  such 
a  great  proportion  in  many  rocks,  would  decompose  the  car- 
bonates and  sulphates,  and,  aided  by  the  presence  of  water, 
the  chlorides  both  of  the  rocky  strata  and  the  sea ;  while  the 
organic  matters  and  the  fossil  carbon  would  be  burned  by  the 
atmospheric  oxygen.  From  these  reactions  would  result  a 
fused  mass  of  silicates  of  alumina,  alkalies,  lime,  magnesia, 
iron,  etc. ; .  while  all  the  carbon,  sulphur,  and  chlorine,  in 
the  form  of  acid  gases,  mixed  with  watery  vapor,  azote,  and 
a  probable  excess  of  oxygen,  would  form  an  exceedingly  dense 
atmosphere.  When  the  cooling  permitted  condensation,  an 
acid  rain  would  fall  upon  the  heated  crust  of  the  earth,  de- 
composing the  silicates,  and  giving  rise  to  chlorides  and  sul- 
1  A 


2     THEOKY  OF  IGNEOUS  ROCKS  AND  VOLCANOES.     [I. 

phates  of  the  various  bases,  while  the  separated  silica  would 
probably  take  the  form  of  crystalline  quartz. 

In  the  next  stage,  the  portions  of  the  primitive  crust  not 
covered  by  the  ocean  undergo  a  decomposition  under  the  influ- 
ence of  the  hot  moist  atmosphere  charged  with  carbonic  acid, 
and  the  feldspathic  silicates  are  converted  into  clays  with 
separation  of  an  alkaline  silicate,  which,  decomposed  by  the 
carbonic  acid,  finds  its  way  to  the  sea  in  the  form  of  alkaline 
bicarbonate,  where,  having  first  precipitated  any  dissolved  ses- 
quioxides,  it  changes  the  dissolved  lime-salts  into  bicarbonate. 
This,  precipitated  chemically  or  separated  by  organic  agencies, 
gives  rise  to  limestones,  the  chloride  of  calcium  being  at  the 
same  time  replaced  by  common  salt.*  The  separation  from 
the  waters  of  the  ocean  of  gypsum  and  sea-salt,  and  of  the 
salts  of  potash  by  the  agency  of  marine  plants,  and  by  the 
formation  of  glauconite,  are  considerations  foreign  to  our  pres- 
ent study. 

In  this  way  we  obtain  a  notion  of  the  processes  by  which, 
from  a  primitive  fused  mass,  may  be  generated  the  silicious, 
calcareous,  and  argillaceous  rocks  which  make  up  the  greater 
part  of  the  earth's  crust,  and  we  also  understand  the  source  of 
the  salts  of  the  ocean.  But  the  question  here  arises  whether 
this  primitive  crystalline  rock,  which  probably  approached  to 
dolerite  in  its  composition,  is  now  anywhere  visible  upon  the 
earth's  surface.  It  is  certain  that  the  oldest  known  rocks  are 
stratified  deposits  of  limestone,  clay,  and  sands,  generally  in  a 
highly  altered  condition,  but  these,  as  well  as  more  recent 
strata,  are  penetrated  by  various  injected  rocks,  such  as  granites, 
trachytes,  syenites,  porphyries,  dolerites,  phonolites,  etc.  These 
offer  in  their  mode  of  occurrence,  not  less  than  their  compo- 
sition, so  many  analogies  with  the  lavas  of  modern  volcanoes, 
that  they  also  are  universally  supposed  to  be  of  igneous  origin, 
and  to  owe  their  peculiarities  to  slow  cooling  under  pressure. 
This  conclusion  being  admitted,  we  proceed  to  inquire  into  the 
sources  of  these  liquid  masses  which,  from  the  earliest  known 
geological  period  up  to  the  present  day,  have  been  from  time 

*  See  in  this  connection  the  note  appended,  page  10.  ' 


L]  THEORY  OF  IGNEOUS  ROCKS  AND  VOLCANOES.  3 

to  time  ejected  from  below.  They  are  generally  regarded  as 
evidences  both  of  the  igneous  fusion  of  the  interior  of  our 
planet,  and  of  a  direct  communication  between  the  surface  and 
the  fluid  nucleus,  which  is  supposed  to  be  the  source  of  the 
various  ejected  rocks. 

These  intrusive  masses,  however,  offer  very  great  diversities 
in  their  composition,  from  the  highly  silicious  and  feldspathic 
granites,  eurites,  and  trachytes,  in  which  lime,  magnesia,  and 
iron  are  present  in  very  small  quantities,  and  in  which  potash 
is  the  predominant  alkali,  to  the  denser  basic  rocks,  dolerite, 
diorite,  trap,  and  basalt ;  in  these,  lime,  magnesia,  and  iron-oxide 
are  abundant,  and  soda  prevails  over  the  potash.  To  account 
for  these  differences  in  the  composition  of  the  injected  rocks, 
Phillips,  and  after  him  Durocher,  suppose  the  interior  fluid 
mass  to  have  separated  into  a  denser  stratum  of  the  basic  sili- 
cates, upon  which  a  lighter  and  more  silicious  portion  floats  like 
oil  upon  water ;  and  that  these  two  liquids,  occasionally  more 
or  less  modified  by  a  partial  crystallization  and  eliquation,  or 
by  a  refusion,  give  rise  to  the  principal  varieties  of  silicious  and 
basic  rocks  ;  while  from  the  mingling  of  the  two  zones  of  liquid 
matter  intermediate  rocks  are  formed.  (Phillips's  Manual  of 
Geology,  p.  556,  and  Durocher,  Annales  des  Mines,  1857,  VoL 
I.  p.  217.) 

An  analogous  view  was  suggested  by  Bunsen  in  his  researches 
on  the  volcanic  rocks  of  Iceland,  and  extended  by  Streng  to 
similar  rocks  in  Hungary  and  Armenia.  These  investigators 
suppose  the  existence  beneath  the  earth's  crust  of  a  trachytic 
and  a  pyroxenic  magma  of  constant  composition,  representing 
respectively  the  two  great  divisions  of  rocks  which  we  have 
just  distinguished ;  and  have  endeavored  to  calculate  from  the 
amount  of  silica  in  any  intermediate  variety,  the  proportions  in 
which  these  two  magmas  must  have  been  mingled  to  produce 
it,  and  consequently  the  proportions  of  alumina,  lime,  magnesia, 
iron-oxide  and  alkalies  which  such  a  rock  may  be  expected  to 
contain.  But  the  amounts  thus  calculated,  as  may  be  seen 
from  Dr.  Streng's  results,  do  not  always  correspond  with  the 
results  of  analysis.  (Streng,  Annales  de  Chimie  et  de  Physique, 


4     THEORY  OF  IGNEOUS  ROCKS  AND  VOLCANOES.     [I. 

Third  Series,  Vol.  XXXIX.  p.  52.)  Besides,  there  are  intru- 
sive rocks,  such  as  the  phonolites,  which  are  highly  basic,  and 
yet  contain  but  very  small  quantities  of  lime,  magnesia,  and 
iron-oxide  ;  being  essentially  silicates  of  alumina  and  alkalies, 
in  part  hydrated. 

We  may  here  remark  that  many  of  the  so-called  igneous 
rocks  are  often  of  undoubted  sedimentary  origin.  It  will 
scarcely  be  questioned  that  this  is  true  of  many  granites,  and 
it  is  certain  that  all  the  feldspathic  rocks  coming  under  the 
categories  of  hyperite,  labradorite,  diorite,  and  amphibolite, 
which  make  so  large  a  part  of  the  Laurentian  system  in  North 
America,  are  of  sedimentary  origin.  They  are  here  interstrati- 
fied  with  limestones,  dolomites,  serpentines,  crystalline  gneisses 
and  quartzites,  which  latter  are  often  conglomerate.  The  same 
thing  is  true  of  similar  feldspathic  rocks  in  the  crystalline 
strata  of  the  Green  Mountains.  These  metamorphic  strata 
have  been  exposed  to  conditions  which  have  rendered  some  of 
them  quasi-fluid  or  plastic.  Thus,  for  example,  crystalline 
limestone  may  be  seen  in  positions  which  have  led  many  ob- 
servers to  regard  it  as  intrusive  rock,  although  its  general  mode 
of  occurrence  leaves  no  doubt  as  to  its  sedimentary  origin.  "We 
find  in  the  Laurentian  system  that  the  limestones  sometimes 
envelope  the  broken  and  contorted  fragments  of  the  beds  of 
quartzite,  with  which  thfcy  are  often  interstratified,  and  pene- 
trate like  a  veritable  trap  into  fissures  in  the  quartzite  and 
gneiss.  A  rock  of  sedimentary  origin  may  then  assume  the 
conditions  of  a  so-called  igneous  rock,  and  who  shall  say  that 
any  intrusive  granites,  dolerites,  euphotides,  or  serpentines 
have  an  origin  distinct  from  the  metamorphic  strata  of  the  same* 
kind  which  make  up  such  vast  portions  of  the  older  stratified 
formations  1  To  suppose  that  each  of  these  sedimentary  rocks 
has  also  its  representative  among  the  ejected  products  of  the 
central  fire,  seems  a  hypothesis  not  only  unnecessary,  but,  when 
we  consider  their  varying  composition,  untenable. 

We  are  next  led  to  consider  the  nature  of  the  agencies  which 
have  produced  this  plastic  condition  in  various  crystalline 
rocks.  Certain  facts,  such  as  the  presence  in  them  of  graphite 


L]    THEORY  OF  IGNEOUS  ROCKS  AND  VOLCANOES.     5 

in  contact  with  carbonate  of  lime  and  oxide  of  iron,  not  less 
than  the  presence  of  alkaliferous  silicates  like  the  feldspars  in 
crystalline  limestones,  forbid  us  to  admit  the  ordinary  notion 
of  the  intervention  of  an  intense  heat  such  as  would  produce 
an  igneous  fusion,  and  lead  us  to  consider  the  view  first  put 
forward  by  Poulett  Sorope,*  and  since  ably  advocated  by 
Scheerer  and  by  Elie  de  Beaumont,  of  the  intervention  of  water, 
aided  by  heat,  which  they  suppose  may  communicate  a  plasticity 
to  rocks  at  a  temperature  far  below  that  required  for  their 
igneous  fusion.  The  presence  of  water  in  the  lavas  of  modern 
volcanoes  led  Mr.  Scrope  to  speculate  upon  the  effect  which  a 
small  portion  of  this  element  might  exert,  at  an  elevated  tem- 
perature and  under  pressure,  in  giving  liquidity  to  masses  of 
rock,  and  he  extended  this  idea  from  proper  volcanic  rocks  to 
granites. 

Scheerer,  in  his  inquiry  into  the  origin  of  granite,  has  ap- 
pealed to  the  evidence  afforded  us  by  the  structure  of  this  rock, 
that  the  more  fusible  feldspars  and  mica  crystallized  before  the 
almost  infusible  quartz.  He  also  points  to  the  existence  in 
granite  of  what  he  has  called  pyrognomic  minerals,  such  as 
allanite  and  gadolinite,  which,  when  heated  to  low  redness, 
undergo  a  peculiar  and  permanent  molecular  change,  accom- 
panied by  an  augmentation  in  density  and  a  change  in  chemical 
properties  ;  a  phenomenon  completely  analogous  to  that  offered 
by  titanic  acid  and  chromic  oxide  in  their  change  by  ignition 
from  a  soluble  to  an  insoluble  condition.  These  facts  seem  to 
exclude  the  idea  of  igneous  fusion,  and  point  to  some  other 
cause  of  liquidity.  The  presence  of  natrolite  as  an  integral 
part  of  the  zircon-syenites  of  Xorway,  and  of  talc,  chlorite,  and 
other  hydrous  minerals  in  many  granites  shows  that  water 
was  not  excluded  from  the  original  granitic  paste.  Scheerer 
appeals,  by  way  of  illustration,  to  the  influence  of  small  portions 
of  carbon  and  sulphur  in  greatly  reducing  the  fusing  point  of 
iron.  He  alludes  to  the  experiments  of  Schaf  hautl  and  Wohler, 
which  show  that  quartz  and  apophyllite  may  be  dissolved  by 
heated  water,  under  pressure,  and  recrystallized  on  cooling. 

*  See  Journal  of  Geological  Society  of  London,  Vol.  XII.  p.  326. 


6  THEORY  OF  IGNEOUS   ROCKS  AND   VOLCANOES.  [L 

He  recalls  the  aqueous  fusion  of  many  hydrated  salts,  and 
finally  suggests  that  the  presence  of  a  small  amount  of  water, 
perhaps  five  or  ten  per  cent,  may  suifice,  at  a  temperature  which 
may  approach  that  of  redness,  to  give  to  a  granitic  mass  a 
liquidity  partaking-  at  once  of  the  characters  of  an  igneous  and 
an  aqueous  fusion. 

This  ingenious  hypothesis,  sustained  by  Scheerer  in  his  dis- 
cussion with  Durocher,*  is  strongly  confirmed  by  the  late  ex- 
periments of  Daubree.  He  found  that  common  glass,  a  silicate 
of  lime  and  alkali,  when  exposed  to  a  temperature  of  400°  C., 
in  presence  of  its  own  volume  of  water,  swelled  up  and  was 
transformed  into  an  aggregate  of  crystals  of  wollastonite,  the 
alkali,  with  the  excess  of  silica,  separating,  and  a  great  part  of 
the  latter  crystallizing  in  the  form  of  quartz.  When  the  glass 
contained  oxide  of  iron,  the  wollastonite  was  replaced  by  crys- 
tals of  diopside.  Obsidian  in  the  same  manner  yielded  crystals 
of  feldspar,  and  was  converted  into  a  mass  like  trachyte.  In 
these  experiments  upon  vitreous  alkaliferous  matters,  the  pro- 
cess of  nature  in  the  metamorphosis  of  sediments  is  reversed ; 
but  Daubree  found  still  farther  that  kaolin,  when  exposed  to  a 
heat  of  400°  C.  in  the  presence  of  a  soluble  alkaline  silicate,  is 
converted  into  crystalline  feldspar,  while  the  excess  of  silica 
separates  in  the  form  of  quartz.  He  found  natural  feldspar 
and  diopside  to  be  extremely  stable  in  the  presence  of  alkaline 
solutions.  These  beautiful  results  were  communicated  to  the 
French  Academy  of  Sciences  on  the  16th  of  November  last, 
and,  as  the  author  well  remarked,  enable  us  to  understand  the 
part  which  water  may  play  in  giving  origin  to  crystalline  min- 
erals in  lavas  and  intrusive  rocks.  The  swelling  up  of  the 
glass  also  shows  that  water  gives  a  mobility  to  the  particles  of 
the  glass  at  a  temperature  far  below  that  of  its  igneous  fusion. 

I  had  already  shown  in  the  Report  of  the  Geological  Sur- 

*  See  for  the  arguments  on  the  two  sides,  Bulletin  of  the  Geol.  Soc.  of 
France,  Second  Series,  Vol.  IV.  pp.  468,  1018 ;  VI.  644  ;  VII.  276 ;  VIII. 
500 ;  also,  Elie  de  Beaumont,  Ibid.,  Vol.  IV.  p.  1312.  See  also  the  re- 
cent microscopical  observations  of  Mr.  Sorby,  confirming  the  theory  of  the 
aqueo-igneous  origin  of  granite  in  the  L.  E.  &  D.  Phil.  Mag.,  February, 
1858. 


I.]          THEORY  OF  IGNEOUS  ROCKS  AND  VOLCANOES.  7 

vey  of  Canada  for  1856,  p.  479,  that  the  reaction  between 
alkaline  silicates  and  carbonates  of  lime,  magnesia  and  iron  at  a 
temperature  of  100°  C.  gives  rise  to  silicates  of  these  bases,  and 
enables  us  to  explain,  their  production  from  a  mixture  of  car- 
bonates and  quartz,  in  the  presence  of  a  solution  of  alkaline 
carbonate.  I  there  also  suggested  that  the  silicates  of  alumina 
in  sedimentary  rocks  may  combine  with  alkaline  silicates  to 
form  feldspars  and  mica,  and  that  it  would  be  possible  to  crys- 
tallize these  minerals  from  hot  alkaline  solutions  in  sealed 
tubes.  In  this  way  I  explained  the  occurrence  of  these  sili- 
cates in  altered  fossiliferous  strata.  My  conjectures  are  now 
confirmed  by  the  experiments  of  Daubree,  which  serve  to 
complete  the  demonstration  of  my  theory  of  the  normal  meta- 
morphisni  of  sedimentary  rocks  by  the  interposition  of  heated 
alkaline  solutions. 

But  to  return  to  the  question  of  intrusive  rocks  :  Calculations 
based  on  the  increasing  temperature  of  the  earth's  crust  as  we 
descend,  lead  to  the  belief  that  at  a  depth  of  about  twenty-five 
miles  the  heat  must  be  sufficient  for  the  igneous  fusion  of  ba- 
salt. The  recent  observations  of  Hopkins,  however,  show  that 
the  melting  points  of  various  bodies,  such  as  wax,  sulphur  and 
resin,  are  greatly  and  progressively  raised  by  pressure,  so  that 
from  analogy  we  may  conclude  that  the  interior  portions  of  the 
earth  are,  although  ignited,  solid  from  great  pressure.  This 
conclusion  accords  with  the  mathematical  deductions  of  Mr. 
Hopkins,  who,  from  the  precession  of  the  equinoxes,  calculates 
the  solid  crust  of  the  earth  to  have  a  thickness  of  800  or  1,000 
miles.  Similar  investigations  by  Mr.  Hennessey,  however,  as- 
sign 600  miles  as  the  maximum  thickness  of  the  crust.  The 
region  of  liquid  fire  being  thus  removed  so  far  from  the  earth's 
surface,  Mr.  Hopkins  suggests  the  existence  of  lakes  or  limited 
basins  of  molten  matter,  which  serve  to  feed  the  volcanoes. 

Now  the  supposed  mode  of  formation  of  the  primitive  molten 
crust  of  the  earth  would  naturally  exclude  all  combined  or 
intermingled  water ;  while  all  the  sedimentary  rocks  are  neces- 
sarily permeated  by  this  liquid,  and  consequently  in  a  condition 
to  be  rendered  semi-fluid  by  the  application  of  heat  as  supposed 


8  THEORY  OF  IGNEOUS  ROCKS  AND  VOLCANOES.  [I. 

in  the  theory  of  Scrope  and  Scheerer.  If  now  we  admit  that 
all  igneous  rocks,  ancient  plutonic  masses  as  well  as  modern 
lavas,  have  their  origin  in  the  liquefaction  of  sedimentary 
strata,  we  at  once  explain  the  diversities  in  their  composition. 
We  can  also  understand  why  the  products  of  volcanoes  in  dif- 
ferent regions  are  so  unlike,  and  why  the  lavas  of  the  .same 
volcano  vary  at  different  periods.  We  find  an  explanation  of 
the  water  and  carbonic  acid  which  are  such  constant  accompani- 
ments of  volcanic  action,  as  well  as  the  hydrochloric  acid,  sul- 
phuretted hydrogen,  and  sulphuric  acid,  which  are  so  abundantly 
evolved  by  certain  volcanoes.  The  reaction  between  silica  and 
carbonates  must  give  rise  to  carbonic  acid,  and  the  decompo- 
sition of  sea-salt  in  saliferous  strata  by  silica,  in  the  presence  of 
water,  will  generate  hydrochloric  acid ;  while  gypsum  in  the 
same  way  will  evolve  its  sulphur  in  the  form  of  sulphurous 
acid  mixed  with  oxygen.  The  presence  of  fossil  plants  in  the 
melting  strata  would  generate  carburetted  hydrogen  gases, 
whose  reducing  action  would  convert  the  sulphurous  acid  into 
sulphuretted  hydrogen ;  or  the  reducing  agency  of  the  carbona- 
ceous matters  might  give  rise  to  sulphuret  of  calcium,  which 
would  be,  in  its  turn,  decomposed  by  carbonic  acid  or  other- 
wise. The  intervention  of  such  matters  in  volcanic  phenom- 
enon is  indicated  by  the  recent  investigations  of  Deville,  who 
has  found  carburetted  hydrogen  in  the  gaseous  emanations 
of  the  region  of  Etna  and  the  lagoons  of  Tuscany.  The 
ammonia  and  the  nitrogen  of  volcanoes  are  also  in  many  cases 
probably  derived  from  organic  matters  in  the  strata  decom- 
posed by  subterranean  heat.  The  carburetted  hydrogen  and 
bitumen  evolved  from  mud-volcanoes,  like  those  of  the  Crimea 
and  of  Bakou,  and  the  carbonized  remains  of  plants  in  the 
moya  of  Quito,  and  in  the  volcanic  matters  of  the  Island  of 
Ascension,  not  less  than  the  infusorial  remains  found  by  Ehren- 
berg  in  the  ejected  matters  of  most  volcanoes,  all  go  to  show 
that  fossiliferous  sediments  are  very  generally  implicated  in 
volcanic  phenomena. 

It  is  to  Sir  John  F.  W.  Herschel  that  we  owe,  so  far  as  I 
am  aware,  the  first  suggestions  of  the  theory  of  volcanic  action 


I.]    THEORY  OF  IGNEOUS  ROCKS  AND  VOLCANOES. 

which  I  have  here  brought  forward.  In  a  letter  to  Sir  Charles 
Lyell,  dated  February  20,  1836  (Proceedings  Geol.  Soc.,  Lon- 
don, Vol.  XI.  p.  548),  he  maintains  that  with  the  accumulation 
of  sediment  the  isothermal  lines  in  the  earth's  crust  must 
rise,  so  that  strata  buried  deep  enough  will  be  crystallized  and 
metamorphosed,  and  eventually  be  raised,  with  their  included 
water,  to  the  melting-point.  This  will  give  rise  to  evolutions 
of  gases  and  vapors,  earthquakes,  volcanic  explosions,  etc.,  all 
of  which  results  must,  according  to  known  laws,  follow  from 
the  fact  of  a  high  central  temperature;  while  from  the  me- 
chanical subversion  of  the  equilibrium  of  pressure,  following 
upon  the  transfer  of  sediments,  while  the  yielding  surface 
reposes  upon  a  mass  of  matter  partly  liquid  and  partly  solid, 
we  may  explain  the  phenomena  of  elevation  and  subsidence. 
Such  is  a  summary  of  the  views  put  forward  more  than  twenty 
years  since  by  this  eminent  philosopher,  which,  although  they 
have  passed  almost  unnoticed  by  geologists,  seem  to  me  to 
furnish  a  simple  and  comprehensive  explanation  of  several 
of  the  most  difficult  problems  of  chemical  and  dynamical 
geology. 

To  sum  up  in  a  few  words  the  views  here  advanced.  "We 
conceive  that  the  earth's  solid  crust  of  anhydrous  and  primitive 
igneous  rock  is  everywhere  deeply  concealed  beneath  its  own 
ruins,  which  form  -a  great  mass  of  sedimentary  strata,  per- 
meated by  water.  As  heat  from  beneath  invades  these  sedi- 
ments, it  produces  in  them  that  change  which  constitutes 
normal  metamorphism.  These  rocks,  at  a  sufficient  depth, 
are  necessarily  in  a  state  of  igneo-aqueous  fusion,  and  in  the 
event  of  fracture  of  the  overlying  strata,  may  rise  among  them, 
taking  the  form  of  eruptive  rocks.  Where  the  nature  of  the 
sediments  is  such  as  to  generate  great  amounts  of  elastic  fluids 
by  their  fusion,  earthquakes  and  volcanic  eruptions  may  result, 
and  these,  other  things  being  equal,  will  be  most  likely  to 
occur  under  the  more  recent  formations.* 

[XoTE  to  page  2.  —  I  have  since  pointed  out  that  the  evidences  of  a 
similar  process  are  still  to  be  seen  in  the  granites  and  crystalline  schists 

*  See  further  in  this  connection  Essays  VI.  and  VII. 


10    THEORY  OF  IGNEOUS  ROCKS  AND  VOLCANOES.     I.] 

of  eozoic  ages  which  in  many  regions  are  decomposed  to  great  depths, 
the  feldspar  being  converted  into  kaolin,  while  the  hornblende  has 
lost  its  protoxide  bases,  the  peroxidized  iron  and  the  silica  remaining 
behind.  This  change  has  affected  the  crystalline  rocks  of  the  southern 
United  States  and  of  Brazil  to  depths  of  a  hundred  feet  or  more,  and 
doubtless  at  one  time  extended  to  all  such  rocks  as  were  above  the 
surface  of  the  ocean.  The  absence  of  this  decayed  material  from  certain 
regions  of  crystalline  rocks  is  to  be  attributed  to  its  subsequent  removal 
by  denudation,  a  process  which  in  the  northern  parts  of  Europe  and 
America  terminated  at  the  close  of  the  pliocene  period,  when  the  remain- 
ing softened  material  was  swept  away  by  the  action  of  water  and  ice, 
and  the  hard  and  unchanged  rocks  beneath  were  exposed  and  glaciated, 
since  which  time  the  chemical  decomposition  of  the  surface  has  been 
insigniiicant.  It  is  this  process  which  was  called  by  Dolomieu  the 
maladie  du  granit,  and  ascribed  by  him  to  the  influence  of  carbonic-acid 
gas  from  subterranean  sources.  It  was,  however,  in  my  opinion  a  uni- 
versal phenomenon,  and  dependent  upon  the  peculiar  composition  of  the 
atmosphere  in  early  times.  These  decomposed  strata  furnished  the  great 
deposits  of  clay  and  sand  of  the  paleozoic  and  later  periods  ;  and  from 
them  was  dissolved  the  iron  which  in  various  forms  is  found  at  different 
horizons  in  the  uncrystalline  rocks  ;  while  the  silica  and  the  alkaline  and 
earthy  carbonates,  removed  in  a  soluble  form  from  these  decaying  eozoic 
rocks,  have  generated  the  limestones,  dolomites,  and  various  silicious  de- 
posits. (See  Proceedings  Boston  Society  of  Natural  History  for  October 
15,  1873.) 

In  the  Proceedings  of  the  same  Society  for  February  18,  1874,  I  have 
called  attention  to  the  fact  that  the  clay  resulting  from  this  decay  of 
rocks  remains  for  many  days  suspended  in  pure  water,  though  not  in 
waters  even  slightly  saline,  and  is  therefore  readily  precipitated  in  a  few 
hours  when  the  turbid  fresh  waters  mingle  with  those  of  jthe  sea,  thus 
forming  fine  argillaceous  sediments.  The  geological  significance  of  this 
fact  was,  it  is  believed,  first  pointed  out  in  1861  by  Mr.  Sid  ell  in  Hum- 
phreys and  Abbot's  Report  on  the  Physics  and  Hydraulics  of  the  Missis- 
sippi River  (Appendix  A,  page  xi. ),  where  he  applied ,  it  to  explain 
the  accumulations  of  mud  at  this  river's  mouth.  Many  chemical  pre- 
cipitates, in  like  manner,  which  may  be  washed  on  a  filter  with  acid 
or  saline  solutions,  readily  pass  through  its  pores  if  suspended  in  pure 
water.  I  have  sought  to  explain  these  phenomena  by  the  principle  that 
saline  matters  reduce  the  cohesion  between  water  and  the  suspended 
particles,  thus  allowing  gravity  and  their  own  cohesion  to  come  into 
play.  Guthrie  (Proceedings  Royal  Society,  XIV.)  has  shown  that  the 
addition  of  small  quantities  of  saline  matters  to  water  diminishes  the  size 
of  its  drops,  evidently  for  the  same  reason.] 


ON    SOME    POINTS    IN    CHEMICAL 
GEOLOGY. 

(1869.) 

A  paper  with  the  above  title  was  sent  to  the  Geological  Society  of  London  in 
August,  1858,  and  read  before  that  body,  January,  1859.  An  abstract  of  it  appeared 
in  the  L.  E.  &  D.  Philosophical  Magazine  for  February,  and  it  was  published  in  full  in 
the  Quarterly  Journal  of  the  Geological  Society  for  November,  from  which  it  was  re- 
printed, with  the  addition  of  a  few  notes,  in  the  Canadian  Naturalist  for  December, 
1859.  Such  portions  of  this  paper  as  were  but  a  repetition  of  the  preceding  one  are 
here  omitted ;  what  follows  may  be  regarded  as  a  supplement  to  that. 


WHEN  we  examine  the  waters  charged  with  saline  matters 
which  impregnate  the  great  mass  of  calcareous  strata  constitut- 
ing in  Canada  the  base  of  the  palaeozoic  series,  we  find  that 
only  about  one  half  of  the  chlorine  is  combined  with  sodium ; 
the  remainder  exists  as  chlorides  of  calcium  and  magnesium,  the 
former  predominating,  —  while  sulphates  are  present  only  in 
small  amount.  If  now  we  compare  this  composition,  which 
may  be  regarded  as  representing  that  of  the  palaeozoic  sea,  with 
that  of  the  modern  ocean,  we  find  that  the  chloride  of  calcium 
has  been  in  great  part  replaced  by  common  salt,  —  a  process 
involving  the  intervention  of  carbonate  of  soda,  and  the  for- 
mation of  carbonate  of  lime.  The  amount  of  magnesia  in  the 
sea,  although  diminished  by  the  formation  of  dolomite  and 
magnesite,  is  now  many  times  greater  than  that  of  the  lime ; 
for  so  long  as  chloride  of  calcium  remains  in  the  water,  the  mag- 
nesian  salts  are  not  precipitated  by  bicarbonate  of  soda.* 

When  we  consider  that  the  vast  amount  of  argillaceous  sedi- 

»  See  Report  Geol.  Sunr.  Canada,  1857,  pp.  212-214  ;  Am.  Jour.  Science 
(2),  XXVIII.  pp.  170,  305  ;  and  further,  Essays  VIII.  and  IX. 


12  ON   SOME  POINTS   IN  CHEMICAL  GEOLOGY.  [II. 

mentary  matter  in  the  earth's  strata  has  doubtlessly  been  formed 
by  the  same  process  which  is  now  going  on,  namely,  the  de- 
composition of  feldspathic  minerals,  it  is  evident  that  we  can 
scarcely  exaggerate  the  importance  of  the  part  which  the  alka- 
line carbonates,  formed  in  this  process,  must  have  played  in  the 
chemistry  of  the  seas.  (Page  2.)  We  have  only  to  recall  waters 
like  Lake  Van,  the  natron-lakes  of  Egypt,  Hungary,  and  many 
other  regions,  the  great  amounts  of  carbonate  of  soda  furnished 
by  springs  like  those  of  Carlsbad  and  Vichy,  or  contained  in 
the  waters  of  the  Loire,  the  Ottawa,  and  probably  many  other 
rivers  that  flow  from  regions  of  crystalline  rocks,  to  be  reminded 
that  a  similar  though  much  slower  process  of  decomposition  of 
alkaliferous  silicates  is  still  going  on. 

A  striking  and  important  fact  in  the  history  of  the  sea,  and 
of  most  alkaline  and  saline  waters,  is  the  small  proportion  of 
potash-salts  which  they  contain.  Soda  is  pre-eminently  the 
soluble  alkali ;  while  the  potash  in  the  earth's  crust  is  locked 
up  in  the  form  of  insoluble  orthoclase,  the  soda-feldspars  readily 
undergo  decomposition.  Hence  we  find  in  the  analyses  of 
clays  and  argillites,  that  of  the  alkalies  which  these  rocks  still 
retain,  the  potash  almost  always  predominates  greatly  over  the 
soda.  At  the  same  time  these  sediments  contain  silica  in  ex- 
cess, and  but  small  portions  of  lime  and  magnesia.  These  con- 
ditions are  readily  explained  when  we  consider  the  nature  of 
the  soluble  matters  found  in  the  mineral  waters  which  issue 
from  these  argillaceous  rocks.  I  have  elsewhere  shown  that 
(setting  aside  the  waters  charged  with  soluble  lime  and  mag- 
nesia-salts, issuing  from  limestones  and  from  gypsiferous  and 
saliferous  formations)  the  springs  from  argillaceous  strata  are 
marked  by  the  predominance  of  bicarbonate  of  soda,  often 
with  portions  of  silicate  and  borate,  besides  bicarbonates  of 
lime  and  magnesia,  and  occasionally  of  iron.  The  atmospheric 
waters  filtering  through  such  strata  remove  soda,  lime  and 
magnesia,  leaving  behind  the  silica,  alumina  and  potash,  —  the 
elements  of  granitic  and  trachytic  rocks.  The  more  sandy 
clays  and  argillites  being  most  permeable,  the  action  of  the  in- 
filtrating waters  will  be  more  or  less  complete  ;  while  finer  and 


II.]  ON  SOME  POINTS  IX  CHEMICAL  GEOLOGY.  13 

more  compact  clays  and  marls,  resisting  the  penetration  of  this 
liquid,  will  retain  their  soda,  lime,  and  magnesia,  and  by  sub- 
sequent alteration  will  give  rise  to  basic  feldspars  containing 
lime  and  soda,  and  if  lime  and  magnesia  predominate,  to  horn- 
blende or  pyroxene. 

The  presence  or  absence  of  iron  in  sediments  demands  es- 
pecial consideration,  since  its  elimination  requires  the  interpo- 
sition of  organic  matters,  which,  by  reducing  the  peroxide  to 
the  condition  of  protoxide,  render  it  soluble  in  water,  either 
as  bicarbonate  or  combined  with  some  organic  acid.  This 
action  of  waters  holding  organic  matter  upon  sediments  con- 
taining iron-oxide  has  been  described  by  Bischof  and  many 
other  writers,  particularly  by  Dr.  J.  W.  Dawson  *  in  a  paper  on 
the  coloring  matters  of  some  sedimentary  rocks,  and  is  applica- 
ble to  all  cases  where  iron  has  been  removed  from  certain  strata 
and  accumulated  in  others.  This  is  seen  in  the  fire-clays  and 
iron-stones  of  the  coal-measures,  and  in  the  white  clays  associat- 
ed with  great  beds  of  green-sand  (essentially  a  silicate  of  iron) 
in  the  cretaceous  series  of  Kew  Jersey.  Similar  alternations 
of  white  feldspathic  beds  with  others  of  iron-ore  occur  in  the 
Green  Mountain  rocks  of  Canada,  and  on  a  still  more  remark- 
able scale  in  those  of  the  Laurentian  series.  We  may  probably 
look  upon  the  formation  of  beds  of  iron-ore  as  in  all  cases  due 
to  the  intervention  of  organic  matters  ;  •  so  that  its  presence,  not 
less  than  that  of  graphite,  affords  evidence  of  the  existence  of 
organic  life  at  the  time  of  the  deposition  of  these  old  crystal- 
line rocks. 

The  agency  of  sulphuric  and  muriatic  acids,  from  volcanic 
and  other  sources,  is  not,  however,  to  be  excluded  in  the  solu- 
tion of  oxide  of  iron  and  other  metallic  oxides.  The  oxidation 
of  pyrites,  moreover,  gives  rise  to  solutions  of  iron  and  alumina- 
salts,  the  subsequent  decomposition  of  which,  by  alkaline  or 
earthy  carbonates,  will  yield  oxide  of  iron  and  alumina ;  the 
absence  of  the  latter  element  serves  perhaps  to  characterize  the 
iron-ores  of  organic  origin,  t  In  this  way  the  deposits  of  emery, 

*  Quar.  Jour.  Geol.  Soc.,  Vol.  V.  p.  25. 

f  The  occurrence  of  hydrated  mixtures  of  oxide  of  iron  and  alumina,  like 


14  ON   SOME  POINTS   IN   CHEMICAL   GEOLOGY.  [II. 

which  is  a  mixture  of  crystallized  alumina  with  oxide  of  iron, 
have  doubtless  been  formed. 

Waters  deficient  in  organic  matters  may  remove  soda,  lime, 
and  magnesia  from  sediments,  and  leave  the  granitic  elements 
intermingled  with  oxide  of  iron ;  while  on  the  other  hand,  by 
the  admixture  of  organic  materials,  the  whole  of  the  iron  may 
be  removed  from  strata  which  will  still  retain  the  lime  and  soda 
necessary  for  the  formation  of  basic  feldspars.  The  fact  that 
bicarbonate  of  magnesia  is  much  more  soluble  than  bicarbonate 
of  lime,  is  also  to  be  taken  into  account  in  considering  these 
reactions. 

The  study  of  the  chemistry  of  mineral  waters,  in  connection 
with  that  of  sedimentary  rocks,  shows  us  that  the  result  of 
processes  continually  going  on  in  nature  is  to  divide  the  silico- 
argillaceous  rocks  into  two  great  classes  (mentioned  on  page 
3),  —  the  one  characterized  by  an  excess  of  silica,  by  the  pre- 
dominance of  potash,  and  by  the  small  amounts  of  lime,  mag- 
nesia and  soda,  and  represented  by  the  granites  and  trachytes ; 
while  in  the  other  class  silica  and  potash  are  less  abundant, 
and  soda,  lime  and  magnesia  prevail,  giving  rise  to  pyroxenes 
and  triclinic  feldspars.  The  metamorphism  and  displacement 
of  such  sediments  may  thus  enable  us  to  explain  the  origin  of 
the  different  varieties  of  plutonic  rocks  without  calling  to  our 
aid  the  ejections  of  the  central  fire. 

Mr.  Babbage  *  has  shown  that  the  horizons  or  surfaces  of 
equal  temperature  in  the  earth's  crust  must  rise  and  fall,  as  a 
consequence  of  the  accumulation  of  sediment  in  some  parts 
and  its  removal  from  others,  producing  thereby  expansion  and 
contraction  in  the  materials  of  the  crust,  and  thus  giving  rise 
to  gradual  and  wide-spread  vertical  movements.  Sir  John  Her- 


bauxite,  serves  to  show  an  intimate  relation  between  the  origin  of  these  two 
bases  in  an  uncombined  state.  Hydrous  alumina,  gibbsite,  is  moreover  found 
incrusting  limonite,  and  the  existence  of  compounds  like  mellite  and  pigotite,  in 
which  alumina  is  united  to  organic  acids,  shows  that  this  base  may,  under  cer- 
tain conditions,  be  set  free  in  a  soluble  condition. 

*  On  the  Temple  of  Serapis,  Proc.  Geol.  Soc.,  Vol.  II.  p.  73.    • 


IL]  ON  SOME  POINTS  IN  CHEMICAL  GEOLOGY.  15 

schel*  subsequently  showed  that,  as  a  result  of  the  internal 
heat  thus  retained  by  accumulated  strata,  sediments  deeply 
enough  buried  will  become  crystallized,  and  ultimately  be  raised, 
with  their  included  water,  to  the  melting-point.  From  the 
chemical  reactions  at  this  elevated  temperature  gases  and  vapors 
will  be  evolved,  and  earthquakes  and  volcanic  eruptions  will 
result.  At  the  same  time  the  disturbance  of  the  equilibrium 
of  pressure  consequent  upon  the  transfer  of  sediments,  while 
the  yielding  surface  reposes  upon  a  mass  of  matter  partly  liquid 
and  partly  solid,  will  enable  us  to  explain  the  phenomena  of 
elevation  and  subsidence. 

According,  then,  to  Sir  John  Herschel's  view,  all  volcanic 
phenomena  have  their  source  in  sedimentary  deposits ;  and  this 
ingenious  hypothesis,  which  is  a  necessary  consequence  of  a 
high  central  temperature,  explains  in  a  most  satisfactory  man- 
ner the  dynamical  phenomena  of  volcanoes,  and  many  other 
obscure  points  in  their  history,  as,  for  instance,  the  indepen- 
dent action  of  adjacent  volcanic  vents,  and  the  varying  nature 
of  their  ejected  products.t  Not  only  are  the  lavas  of  diiferent 
volcanoes  very  unlike,  but  those  of  the  same  crater  vary  at  dif- 
ferent times ;  the  same  is  true  of  the  gaseous  matters,  hydro- 
chloric, hydrosulphuric,  and  carbonic  acids.  As  the  ascending 
heat  penetrates  saliferous  strata,  we  shall  have  hydrochloric 
acid,  from  the  decomposition  of  sea-salt  by  silica  in  the  presence 
of  water ;  while  gypsum  and  other  sulphates,  by  a  similar  re- 
action, would  lose  their  sulphur  in  the  form  of  sulphurous  acid 
•  and  oxygen.  The  intervention  of  organic  matters,  either  by 
direct  contact  or  by  giving  rise  to  reducing  gases,  would  con- 
vert the  sulphates  into  sulphurets,  which  would  yield  sulphu- 
retted hydrogen  when  decomposed  by  water  and  silica  or  by  car- 
bonic acid ;  the  latter  being  the  result  of  the  action  of  silica 
upon  earthy  carbonates.  We  conceive  the  ammonia  so  often 
found  among  the  products  of  volcanoes  to  be  evolved  from  the 
heated  strata,  where  it  exists  in  part  as  ready-formed  ammonia 
(which  is  absorbed  from  air  and  water,  and  pertinaciously  re- 

*  On  the  Temple  of  Serapis,  Proc.  Geol.  Soc.,  Vol.  II.  pp.  548,  596. 
f  For  a  further  development  of  this  theory,  see  Essays  VI.  and  VII. 


16  ON  SOME  POINTS  IN   CHEMICAL  GEOLOGY.  [II. 

tained  by  argillaceous  sediments),  and  is  in  part  formed  by  the 
action  of  heat  upon  azotized  organic  matter  present  in  these 
strata,  as  already  maintained  by  Bischof.*  Nor  can  we  hesi- 
tate to  accept  this  author's  theory  of  the  formation  of  boracic 
acid  from  the  decomposition  of  borates  by  heat  and  aqueous 
vapor,  t 

The  metamorphism  of  sediments  in  situ,  their  displacement 
in  a  pasty  condition  from  igneo-aqueous  fusion  as  plutonic 
rocks,  and  their  ejection  as  lavas,  with  attendant  gases  and 
vapors  are,  then,  all  results  of  the  same  cause,  and  depend 
upon  the  differences  in  the  chemical  composition  of  the  sedi- 
ments, the  temperature,  and  the  depth  to  which  they  are  buried  : 
while  the  unstratified  nucleus  of  the  earth,  which  is  doubtless 
anhydrous,  and,  according  to  the  calculations  of  Messrs.  Hop- 
kins and  Hennessey,  probably  solid  to  a  great  depth,  intervenes 
in  the  phenomena  under  consideration  only  as  a  source  of 
heat.J 

*  Lehrbuch  der  Geologie,  Vol.  II.  pp.  115-122. 

f  Ibid.,  Vol.  I.  p.  669. 

J  The  notion  that  volcanic  phenomena  have  their  seat  in  the  sedimentary 
formations  of  the  earth's  crust,  and  are  dependent  upon  the  combustion  of 
organic  matters,  is,  as  Humboldt  remarks,  one  which  belongs  to  the  infancy 
of  geognosy.  (Cosmos,  Vol.  V.  p.  443.  Otte's  translation.)  In  1834,  Christian 
Keferstein  published  his  Naturgeschichte  des  Erdkorpers,  in  which  he  main- 
tains that  all  crystalline  non-stratified  rocks,  from  granite  to  lava,  are  products 
of  the  transformation  of  sedimentary  strata,  in  part  very  recent,  and  that 
there  is  no  well-defined  line  to  be  drawn  between  neptunian  and  volcanic  rocks, 
since  they  pass  into  each  other.  Volcanic  phenomena,  according  to  him,  have 
their  origin,  not  in  an  igneous  fluid  centre,  nor  an  oxidizing  metallic  nucleus, 
but  in  known  sedimentary  formations,  where  they  are  the  result  of  a  peculiar 
process  of  fermentation,  which  crystallizes  and  arranges  in  new  forms  the  ele- 
mente  of  the  sedimentary  strata,  with  evolution  of  heat  as  an  accompaniment 
of  the  chemical  process.  (Naturgeschichte,  Vol.  I.  p.  109  ;  also  Bull.  Soc. 
Geol.  de  France  (1),  Vol.  VII.  p.  197.) 

These  remarkable  conclusions  were  unknown  to  me  at  the  time  of  writing 
this  paper,  and  seem  indeed  to  have  been  entirely  overlooked  by  geological 
writers  ;  they  are,  as  will  be  seen,  in  many  respects  an  anticipation  of  the 
Views  of  Herschel  and  my  own  ;  although  in  rejecting  the  influence  of  an 
incandescent  nucleus  as  a  source  of  heat,  he  has,  as  I  conceive,  excluded  the 
exciting  cause  of  that  chemical  change,  which  he  has  not  inaptly  described  as 
a  process  of  fermentation,  and  which  is  the  source  of  all  volcanic  and  plutonic 
phenomena.  See  in  this  connection  Essays  I.  and  VII.  of  the  present  volume. 


H]  ON  SOME  POINTS  IN   CHEMICAL  GEOLOGY.  17 

The  volcanic  phenomena  of  the  present  day  appear,  so  far  as 
I  am  aware,  to  be  confined  to  regions  covered  by  the  more  re- 
cent secondary  and  tertiary  deposits,  which  we  may  suppose 
the  central  heat  to  be  still  penetrating  (as  shown  by  Mr.  Bab- 
bage),  a  process  which  has  long  since  ceased  in  the  palaeozoic 
regions.  Both  normal  metamorphism  and  volcanic  action  are 
generally  connected  with  elevations  and  foldings  of  the  earth's 
crust,  all  of  which  phenomena  we  conceive  to  have  a  common 
cause,  and  to  depend  upon  the  accumulation  of  sediments  and 
the  subsidence  consequent  thereon,  as  maintained  by  Mr.  James 
Hall  in  his  theory  of  mountains.* 


*  See,  for  an  exposition  of  the  views  of  Professor  Hall,  Essays  V.  and 
VII.  of  the  present  volume. 


III. 


THE  CHEMISTRY  OF  METAMORPHIC 
ROCKS. 

(1863.) 


This  paper  was  read  before  the  Dublin  Geological  Society,  April  10,  1863,  published 
in  the  Dublin  Quarterly  Journal  for  July,  and  reprinted  in  the  Canadian  Naturalist 
for  the  same  year.  The  notions  expressed  in  the  first  paragraph  as  to  the  exist- 
ence of  crystalline  strata  of  all  geological  ages,  the  results  of  a  subsequent  alteration 
of  palaeozoic,  uieseozoic,  and  even  of  cenozoic  sediments,  are  in  strict  accordance  with 
those  which  were  then  (and  are  even  now)  maintained  by  most  of  the  authorities  in 
geology  ;  and  at  that  time  had  scarcely  been  questioned.  Hence  it  is  that  the  rocks 
of  what  are  here  designated  the  third  and  fourth  series  were,  in  conformity  with  the 
conclusions  generally  accepted,  referred  to  the  palaeozoic  age.  It  will,  however,  be 
seen  that  I  had  at  that  time  no  doubt  that  the  rocks  of  the  third  (or  Green  Mountain) 
series,  then  regarded  as  altered  Lower  Silurian,  were,  as  Macfarlane  had  already  main- 
tained, the  equivalents  of  a  part  at  least  of  the  Primitive  Slate  or  Urschiefer  formation 
of  Norway.  He,  as  is  here  stated,  supposed  the  Huronian  to  represent  another  part 
of  the  same  formation  ;  while  Bigsby  soon  after  expressed  the  opinion  that  the  Huro- 
nian and  the  Urschiefer  are  the  same.  My  own  extended  studies  of  these  rocks  in  the 
Green  Mountains,  in  New  Brunswick,  and  on  Lakes  Superior  and  Huron,  have  since 
convinced  me  that  this  view  is  correct,  and  that  the  Green  Mountain  series  is  repre- 
sented in  the  crystalline  strata  around  the  great  lakes  just  mentioned ;  and,  moreover, 
that  both  this  series  and  the  crystalline  rocks  of  the  fourth  or  White  Mountain  series 
existed  in  their  present  crystalline  form  before  the  deposition  of  the  oldest  Cambrian 
sediments.  The  further  history  of  these  crystalline  series  will  be  found  in  an  Essay 
on  the  Geognosy  of  the  Appalachians  (XIII.  of  the  present  volume),  and  in  its 
Appendix.  In  this  connection  the  reader  is  also  referred  to  portions  of  those  on 
Granitic  Rocks  (XI.),  on  Alpine  Geology  (XIV.),  and  to  the  third  part  of  that  on  Cam- 
brian and  Silurian  (XV.).  See  also  a  note  to  the  present  paper  (page  33). 

These  conclusions  carry  back  the  origin  of  these  two  series  of  crystalline  rocks 
to  a  much  more  remote  period  in  geological  history  than  was  formerly  supposed  ;  but 
the  chemical  principles  laid  down  in  this  paper  I  believe  to  be  still  true,  and  of 
general  application,  and  for  this  reason  it  is  reprinted  with  the  omission  of  a  few 
sentences  which,  by  their  reference  to  the  supposed  palaeozoic  age  of  the  crystalline 
rocks  above  referred  to,  might  serve  to  mislead  the  reader. 

While  retaining  the  original  title,  I  however  regard  the  name  of  metamorphic  rod's, 
as  applied  to  crystalline  strata,  an  unfortunate  one,  which  it  would  be  well  to  banish 
from  the  science  of  geology.  Although  it  is  not  to  be  questioned  that  local  and  excep- 
tional agencies,  apparently  hydrothermal,  have -occasionally  given  rise  to  crystalline 
silicated  minerals  in  palaeozoic  and  even  in  more  recent  sediments,  and  may  thus  help 


III.]  THE  CHEMISTRY  OF  METAMORPHIC  ROCKS.  19 

us  to  form  some  conception  of  processes  which  were  universal  in  eozoic  times,  the 
notion  that  any  of  the  great  series  of  crystalline  rocks  are  the  stratigraphical  equiva- 
lents of  formations  elsewhere  known  to  us  as  uncrystalliue  sediments,  will  be  found  to 
rest  on  very  uncertain  evidence.  Those  crystalline  rocks  have  doubtless,  since  their 
deposition,  undergone  certain  molecular  modifications  (by  what  has  been  named 
diagenesis)  which  have  changed  their  original  aspect ;  but  something  of  the  same  sort 
is  to  a  greater  or  less  extent  true  of  many  sedimentary  rocks  to  which  we  do  not  give 
the  name  of  metamorphic.  This  term  has  not  only  come  to  be  familiarly  used  as  a 
synonyme  for  all  crystalline  stratified  rocks,  but  is  associated  with  the  notion  of  a 
profound  epigenic  change  (pseudomorphism)  extended  alike  to  uncrystalline  sediments 
and  to  crystalline  eruptive  rocks  ;  a  notion  has  been  embodied  in  the  assertion  that 
"  regional  metamorphism  is  pseudomorphism  on  a  grand  scale."  See  in  this  connec- 
tion Essay  XIII.  and  its  Appendix. 

AT  a  time  not  very  remote  in  the  history  of  geology,  when  all 
crystalline  stratified  rocks  were  included  under  the  common  des- 
ignation of  primitive,  and  were  supposed  to  belong  to  a  period 
anterior  to  the  fossiliferous  formations,  the  lithologist  confined 
his  studies  to  descriptions  of  the  various  species  of  rocks,  with- 
out reference  to  their  stratigraphical  or  geological  distribution. 
But  with  the  progress  of  geological  science  a  new  problem  is 
presented  to  his  investigation.  While  paleontology  has  shown 
that  the  fossils  of  each  formation  furnish  a  guide  to  its  age 
and  stratigraphical  position,  it  has  been  found  that  sedimentary 
strata  of  all  ages,  up  to  the  tertiary  inclusive,  may  undergo 
such  changes  as  to  obliterate  the  direct  evidences  of  organic 
life ;  and  to  give  to  the  sediments  the  mineralogical  characters 
once  assigned  to  primitive  rocks.*  The 'question  here  arises, 
whether  in  the  absence  of  organic  remains,  or  of  stratigraphical 
evidence,  there  exists  any  means  of  determining,  even  approxi- 
mately, the  geological  age  of  a  given  series  of  crystalline  strati- 
fied rocks;  in  other  words,  whether  the  chemical  conditions 
which  have  presided  over  the  formation  of  sedimentary  rocks 
have  so  far  varied  in  the  course  of  ages,  as  to  impress  upon 
these  rocks  marked  chemical  and  mineralogical  differences.  In 
the  case  of  unaltered  sediments  it  would  be  difficult  to  arrive 
at  any  solution  of  this  question  without  greatly  multiplied 
analyses ;  but  in  the  same  rocks,  when  altered,  the  crystalline 
minerals  which  are  formed,  being  definite  in  their  composition, 
and  varying  with  the  chemical  constitution  of  the  sediments, 

*  See  the  remarks  on  the  preceding  page. 


20  THE  CHEMISTRY  OF  METAMORPHIC  ROCKS.  [III. 

may  perhaps  to  a  certain  extent  become  to  the  geologist  what 
organic  remains  are  in  the  unaltered  rocks,  —  a  guide  to  the 
geological  age  and  succession. 

It  was  while  engaged  in  the  investigation  of  metamorphic 
rocks  of  various  ages  in  North  America,  that  this  problem  sug- 
gested itself;  and  I  have  endeavored  from  chemical  considera- 
tions, conjoined  with  multiplied  observations,  to  attempt  its 
solution.  In  the  Quarterly  Journal  of  the  Geological  Society 
of  London  for  1859  (Essay  II.  of  the  present  volume)  will  be 
found  the  germs  of  the  ideas  on  this  subject,  which  I  shall 
endeavor  to  explain  in  the  present  paper.  It  cannot  be  doubted 
that  in  the  earlier  periods  of  the  world's  history,  chemical  forces 
of  certain  kinds  were  much  more  active  than  at  the  present 
day.  Thus  the  decomposition  of  earthy  and  alkaline  silicates, 
under  the  combined  influences  of  water  and  carbonic  acid, 
would  be  greater  when  this  acid  was  more  abundant  in  the 
atmosphere,  and  when  the  temperature  was  probably  higher 
(page  2).  The  larger  amounts  of  alkaline  and  earthy  carbon- 
ates then  carried  to  the  sea  from  the  decomposition  of  these 
silicates  would  furnish  a  greater  amount  of  calcareous  matter 
to  the  sediments  ;  and  the  chemical  effects  of  vegetation,  both 
on  the  soil  and  on  the  atmosphere,  must  have  been  greater 
during  the  carboniferous  period,  for  example,  than  at  present. 
In  the  spontaneous  decomposition  of  feldspars,  which  may  be 
described  as  silicates  of  alumina  combined  with  silicates  of 
potash,  soda  and  lime,  these  latter  bases  are  removed,  together 
with  a  portion  of  silica ;  and  there  remains,  as  the  final  result 
of  the  process,  a  hydrous  silicate  of  alumina,  which  constitutes 
kaolin  or  clay.  This  change  is  favored  by  mechanical  division  j 
and  Daubree  has  shown  that  by  the  prolonged  attrition  of  frag- 
ments of  granite  under  water,  the  softer  and  readily  cleavable 
feldspar  is  in  great  part  reduced  to  an  impalpable  powder,  while 
the  uncleavable  grains  of  quartz  are  only  rounded,  and  form  a 
readily  subsiding  sand ;  the  water  at  the  same  time  dissolving 
from  the  feldspar  a  certain  portion  of  silica  and  of  alkali.  It  has 
been  repeatedly  observed,  where  potash  and  soda-feldspars  are 
associated,  that  the  latter  is  much  the  more  readily  decomposed, 


III.]  THE  CHEMISTRY  OF  METAMORPHIC  ROCKS.  21 

becoming  friable,  and  finally  being  reduced  to  clay,  while  the 
orthoclase  is  unaltered.  The  result  of  combined  chemical  and 
mechanical  agencies  acting  upon  rocks  which  contain  quartz, 
with  orthoclase  and  a  soda-feldspar  such  as  albite  or  oligoclase, 
would  thus  be  a  sand,  made  up  chiefly  of  quartz  and  potash- 
feldspar,  and  a  finely  divided  and  suspended  clay,  consisting  for 
the  most  part  of  kaolin  and  of  partially  decomposed  soda-feld- 
spar, mingled  with  some  of  the  smaller  particles  of  orthoclase 
and  of  quartz.  With  this  sediment  will  also  be  included  the 
oxide  of  iron,  and  the  earthy  carbonates  set  free  by  the  sub-aerial 
decomposition  of  silicates  like  pyroxene  and  the  anorthic  feld- 
spars, or  formed  by  the  action  of  the  carbonate  of  soda  derived 
from  the  latter  upon  the  lime-salts  and  the  magnesia-salts  of 
sea-water.  The  de"bris  of  hornblende  and  pyroxene  will  also 
be  found  in  this  finer  sediment.  This  process  is  evidently  the 
one  which  must  go  on  in  the  wearing  away  of  rocks  by  aqueous 
agency,  and  explains  the  fact  that  while  quartz,  or  an  excess  of 
combined  silica,  is  for  the  most  part  wanting  in  rocks  which 
contain  a  large  proportion  of  alumina,  it  is  generally  abundant 
in  those  rocks  in  which  potash-feldspar  predominates. 

So  long  as  this  decomposition  of  alkaliferous  silicates  is  sub- 
aerial,  the  silica  and  alkali  are  both  removed  in  a  soluble  form. 
The  process  is  often,  however,  submarine  or  subterranean,  tak- 
ing place  in  buried  sediments  which  are  mingled  with  carbon- 
ates of  lime  and  magnesia.  In  such  cases  the  silicate  of  soda 
set  free  reacts  either  with  these  earthy  carbonates,  or  with  the 
corresponding  chlorides  of  sea-water,  and  forms  in  either  event 
a  soluble  soda-salt,  and  insoluble  silicates  of  lime  and  magnesia 
which  take-  the  place  of  the  removed  silicate  of  soda.  The 
evidence  of  such  a  continued  reaction  between  alkaliferous 
silicates  and  earthy  carbonates  is  seen  in  the  large  amounts  of 
carbonate  of  soda,  with  but  little  silica,  which  infiltrating 
waters  constantly  remove  from  argillaceous  strata ;  thus  giving 
rise  to  alkaline  springs  and  to  natron-lakes.  In  these  waters 
it  will  be  found  that  soda  greatly  predominates,  sometimes 
almost  to  the  exclusion  of  potash.  This  is  due  not  only  to 
the  fact  that  soda-feldspars  are  more  readily  decomposed  than 


22  THE  CHEMISTRY  OF  METAMORPHIC  ROCKS.  [III. 

orthoclase,  but  to  the  well-known  power  of  argillaceous  sedi- 
ments to  abstract  from  water  the  potash- salts  which  it  already 
holds  in  solution.  Thus  when  a  solution  of  silicate,  carbonate, 
sulphate  or  chloride  of  potassium  is  filtered  through  common 
earth,  the  potash  is  taken  up,  and  replaced  by  lime,  magnesia, 
or  soda,  by  a  double  decomposition  between  the  soluble  potash- 
salt  and  the  insoluble  silicates  or  carbonates  of  the  latter  bases. 
Soils,  in  like  manner,  remove  from  infiltrating  waters,  ammonia, 
and  phosphoric  and  silicic  acids,  the  bases  which  were  in  combi- 
nation with  these  being  converted  into  carbonates.  The  drain- 
age-water of  soils,  like  that  of  most  mineral  springs,  contains 
only  carbonates,  chlorides  and  sulphates  of  lime,  magnesia  and 
soda ;  the  ammonia,  potash,  phosphoric  and  silicic  acids  being 
retained  by  the  soil. 

The  elements  which  the  earth  retains  or  extracts  from  waters 
are  precisely  those  which  are  removed  from  it  by  growing 
plants.  These,  by  their  decomposition  under  ordinary  condi- 
tions, yield  their  mineral  matters  again  to  the  soil ;  but  when 
decay  takes  place  in  water,  these  elements  become  dissolved, 
and  hence  the  waters  from  peat-bogs  and  marshes  contain 
large  amounts  of  potash  and  silica  in  solution,  which  are  carried 
to  the  sea,  there  to  be  separated,  —  the  silica  by  protophytes, 
and  the  potash  by  algae,  which  latter,  decaying  on  the  shore, 
or  in  the  ooze  at  the  bottom,  restore  the  alkali  to  the  earth. 
The  conditions  under  which  the  vegetation  of  the  coal-formation 
grew  and  was  preserved  being  similar  to  those  of  peat,  the 
soils  became  exhausted  of  potash,  and  are  seen  in  the  fire-clays 
of  the  carboniferous  period. 

Another  effect  of  vegetation  on  sediments  is  due  to  the  re- 
ducing or  deoxidizing  agency  of  the  organic  matters  from  its 
decay.  These,  as  is  well  known,  reduce  the  peroxide  of  iron 
to  a  soluble  protoxide,  and  remove  it  from  the  soil,  to  be 
afterwards  deposited  in  the  forms  of  iron-ochre  and  iron-ores, 
which  by  subsequent  alteration  become  hard,  crystalline  and 
insoluble.  Thus,  through  the  agency  of  vegetation,  is  the  iron- 
oxide  of  the  sediments  withdrawn  from  the  terrestrial  circula- 
tion ;  and  it  is  evident  that  the  proportion  of  this  element 


III.]  THE  CHEMISTRY  OF   METAMORPHIC   ROCKS.  23 

diffused  in  the  more  recent  sediments  must  be  much  less  than 
in  those  of  ancient  times.  The  reducing  power  of  organic  mat- 
ter is  further  shown  in  the  formation  of  metallic  sulphurets ; 
the  reduction  of  sulphates  having  precipitated  in  this  insoluble 
form  the  heavy  metals,  copper,  lead  and  zinc,  which,  with  iron, 
appear  to  have  been  in  solution  in  the  waters  of  early  times, 
but  are  now  by  this  means  also  abstracted  from  the  circulation, 
and  accumulated  in  beds  and  fahlbands,  or  by  a  subsequent 
process  have  been  redissolved  and  deposited  in  veins.  All 
analogies  lead  us  to  the  conclusion  that  the  primeval  condition 
of  the  metals,  and  of  sulphur,  was,  like  that  of  carbon,  one  of 
oxidation,  and  that  vegetable  life  has  been  the  sole  medium  of 
their  reduction. 

The  source  of  the  carbonates  of  lime  and  magnesia  in  sedi- 
mentary strata  is  twofold  :  —  first,  the  decomposition  of  sili- 
cates containing  these  bases,  such  as  anorthic  feldspars  and 
pyroxene ;  and,  second,  the  action  of  the  alkaline  carbonates 
formed  by  the  decomposition  of  feldspars,  upon  the  chlorides  of 
calcium  and  magnesium  originally  present  in  sea- water  ;  which 
have  thus,  in  the  course  of  ages,  been  in  great  part  replaced^by 
chloride  of  sodium.  The  clay,  or  aluminous  silicate  which  has 
been  deprived  of  its  alkali,  is  thus  at  once  a  measure  of  the 
carbonic  acid  removed  from  the  air,  of  the  carbonates  of  lime 
and  magnesia  precipitated,  and  of  the  amount  of  chloride  of 
sodium  added  to  the  waters  of  the  primeval  ocean. 

The  coarser  sediments,  in  which  quartz  and  orthoclase  prevail, 
are  readily  permeable  to  infiltrating  waters,  which  gradually 
remove  from  them  the  soda,  lime  and  magnesia  which  they 
contain ;  and,  if  organic  matters  intervene,  the  oxide  of  iron ; 
leaving  at  last  little  more  than  silica,  alumina  and  potash,  — 
the  elements  of  granite,  trachyte,  gneiss  and  mica-schist.  On 
the  other  hand,  the  finer  marls  and  clays,  resisting  the  penetra- 
tion of  water,  will  retain  all  their  soda,  lime,  magnesia,  and 
oxide  of  iron ;  and  containing  an  excess  of  alumina,  with  a 
small  amount  of  silica,  will,  by  their  metamorphism,  give  rise 
to  basic  lime-feldspars  and  soda-feldspars,  and  to  pyroxene  and 
hornblende,  —  the  elements  of  diorites  and  dolerites.  In  this 


24  THE  CHEMISTRY  OF  METAMORPHIC  ROCKS.  [III. 

way  the  operation  of  the  chemical  and  mechanical  causes 
which  we  have  traced  naturally  divides  all  the  crystalline 
silico-aluminous  rocks  of  the  earth's  crust  into  two  types. 
These  correspond  to  the  two  classes  of  igneous  rocks,  distin- 
guished first  by  Professor  Phillips,  and  subsequently  by  Duro- 
cher  and  by  Bunsen,  as  derived  from  two  distinct  magmas 
which  these  geologists  imagine  to  exist  beneath  the  solid  crust, 
and  which  the  latter  denominates  the  trachytic  and  pyroxenic 
types.  I  have  however  elsewhere  endeavored  to  show  that  all 
intrusive  or  exotic  rocks  are  probably  nothing  more  than  al- 
tered and  displaced  sediments,  and  have  thus  their  source  with- 
in the  lower  portions  of  the  stratified  crust,  and  not  beneath  it 
(pages  4,  8  and  14). 

It  may  be  well  in  this  place  to  make  a  few  observations  on 
the  chemical  conditions  of  rock-metamorphism.  I  accept  in 
its  widest  sense  the  view  of  Hutton  and  Boue,  that  all  the 
crystalline  stratified  rocks  have  been  produced  by  the  alteration 
of  mechanical  and  chemical  sediments.  The  conversion  of 
these  into  definite  mineral  species  has  been  effected  in  two 
ways  :  first,  by  molecular  changes,  that  is  to  say,  by  crystalli- 
zation, and  a  rearrangement  of  particles ;  and,  secondly,  by 
chemical  reactions  between  the  elements  of  the  sediments. 
Pseudomorphism,  which  is  the  change  of  one  mineral  species 
into  another  by  the  introduction  or  the  elimination  of  some 
element  or  elements,  presupposes  metamorphism;  since  only 
definite  mineral  species  can  be  the  subjects  of  this  process. 
To  confound  metamorphism  with  pseudomorphism,  as  Bis- 
chof,  and  others  after  him,  have  done,  is  therefore  an  error. 
It  may  be  further  remarked,  that,  although  certain  pseudo- 
morphic  changes  may  take  place  in  some  mineral  species,  in 
veins,  and  near  to  the  surface,  the  alteration  of  great  masses 
of  silicated  rocks  by  such  a  process  is  as  yet  an  unproved 
hypothesis.* 

The  cases  of  local  metamorphism  in  proximity  to  intrusive 
rocks  go  far  to  show,  in  opposition  to  the  views  of  certain 
geologists,  that  heat  has  been  one  of  the  necessary  conditions 

*  See  further  on  this  subject  Essay  XIII.  and  its  appendix. 


III.]  THE   CHEMISTRY  OF  METAMOBPHIC  ROCKS.  25 

of  the  change.  The  source  of  this  has  been  generally  supposed 
to  be  from  below;  but  to  the  hypothesis  of  alteration  by 
ascending  heat,  Naumann  has  objected  that  the  inferior  strata 
in  some  cases  escape  change,  and  that,  in  descending,  a  certain 
plane  limits  the  metamorphism,  separating  the'  altered  strata 
above  from  the  unaltered  ones  beneath,  there  being  no  ap- 
parent transition  between  the  two.  This,  taken  in  connection 
with  the  well-known  fact  that  in  many  cases  the  intrusion  of 
igneous  rocks  causes  no  apparent  change  in  the  adjacent  unal- 
tered sediments,  shows  that  heat  and  moisture  are  not  the  only 
conditions  of  metamorphism.  In  1857  I  showed  by  experi- 
ments that,  in  addition  to  these  conditions,  certain  chemical 
reagents  might  be  necessary ;  and  that  water  impregnated  with 
alkaline  carbonates  and  silicates  would,  at  a  temperature  not 
above  that  of  212°  F.,  produce  chemical  reactions  among  the 
elements  of  many  sedimentary  rocks,  dissolving  silica,  and 
generating  various  silicates.*  Some  months  subsequently, 
Daubree  found  that  in  the  presence  of  solutions  of  alkaline 
silicates,  at  temperatures  above  700°  F.,  various  silicious 
minerals,  such  as  quartz,  feldspar  and  pyroxene,  could  be 
made  to  assume  a  crystalline  form  ;  and  that  alkaline  silicates 
in  solution  at  this  temperature  would  combine  with  clay  to 
form  feldspar  and  mica.t  These  observations  were  the  com- 
plement of  my  own,  and  both  together  showed  the  agency  of 
heated  alkaline  waters  to  be  sufficient  to  effect  the  metamor- 
phism of  sediments  by  the  two  modes  already  mentioned,  — 
namely,  by  molecular  changes  and  by  chemical  reactions. 
Following  upon  this,  Daubree  observed  that  the  thermal 
alkaline  spring  of  Plombieres,  with  a  temperature  of  160°  F., 
had  in  the  course  of  centuries  given  rise  to  the  formation  of 
zeolites,  and  other  crystalline  silicated  minerals,  among  the 
bricks  and  cement  of  the  old  Eoman  baths.  From  this  he 
was  led  to  suppose  that  the  metamorphism  of  great  regions 

*  Proc.  Royal  Soc.  of  London,  May  7,  1857;  andPhilos.  Mag.  (4),  XV.  68; 
also  Amer.  Jour.  Science  (2),  XXII.  and  XXV.  435. 

f  Comptes  Rendus  de  1'Acad.,  Nov.  16,  1857;  also  Bull.  Soc.  Geol    de 
France  (2),  XV.  103. 
2 


26  THE   CHEMISTRY  OF  METAMORPHIC  ROCKS.  [III. 

might  have  been  effected  by  hot  springs ;  which,  rising  along 
certain  lines  of  dislocation,  and  thence  spreading  laterally, 
might  produce  alteration  in  strata  near  to  the  surface,  while 
those  beneath  would  in  some  cases  escape  change.*  This 
ingenious  hypothesis  may  serve  in  some  cases  to  meet  the 
difficulty  pointed  out  by  Naumann ;  but  while  it  is  undoubt- 
edly true  in  certain  instances  of  local  metamorphism,  it  seems 
to  be  utterly  inadequate  to  explain  the  complete  and  universal 
alteration  of  areas  of  sedimentary  rocks,  embracing  many  hun- 
dred thousands  of  square  miles.  On  the  other  hand,  the  study 
of  the  origin  and  distribution  of  mineral  springs  shows  that 
alkaline  waters  (whose  action  in  metamorphism  I  first  pointed 
out,  and  whose  efficient  agency  Daubree  has  since  so  well  shown) 
are  confined  to  certain  sedimentary  deposits,  and  to  definite 
stratigraphical  horizons ;  above  and  below  which  saline  waters 
wholly  different  in  character  are  found  impregnating  the  strata. 
This  fact  seems  to  offer  a  simple  solution  of  the  difficulty 
advanced  by  Naumann,  and  a  complete  explanation  of  the 
theory  of  metamorphism  of  deeply  buried  strata  by  the  agency 
of  ascending  heat ;  which  is  operative  in  producing  chemical 
changes  only  in  those  strata  in  which  soluble  alkaline  salts 
are  present,  t 

When  the  sedimentary  strata  have  been  rendered  crystalline 
by  metamorphism,  their  permeability  to  water,  and  their  altera- 
bility,  become  greatly  diminished ;  and  it  is  only  when  again 
broken  down  by  mechanical  agencies  to  the  condition  of  soils 
and  sediments,  that  they  once  more  become  subject  to  the 
chemical  changes  which  have  just  been  described.  Hence, 

*  It  should  be  remembered  that  normal  or  regional  metamorphism  is  in 
no  way  dependent  upon  the  proximity  of  unstratified  or  igneous  rocks,  which 
are  rarely  present  in  metamorphic  districts.  The  ophiolites,  amphibolites, 
euphotides,  diorites,  and  granites  of  such  regions,  which  it  has  been  custom- 
ary to  regard  as  exotic  or  intrusive  rocks,  are  in  most  cases  indigenous. 

+  See  Report  of  the  Geological  Survey  of  Canada,  1853  -  56,  pp.  479,  480  ; 
also  Canadian  Naturalist,  Vol.  VII.  p.  262.  For  a  consideration  of  the  rela- 
tions of  mineral  waters  to  geological  formations,  see  General  Report  on  the 
Geology  of  Canada,  1863,  p.  561,  and  also  Chap.  XIX.  of  the  same  Report, 
on  Sedimentary  and  Metamorphic  Rocks  ;  where  most  of  the  points  touched 
in  the  present  paper  are  discussed  at  greater  length. 


III.]  THE   CHEMISTRY  OF  METAMORPHIC  ROCKS.  27 

the  mean  composition  of  the  argillaceous  sediments  of  any 
geological  epoch,  or,  in  other  words,  the  proportion  between 
the  alkalies  and  the  alumina,  will  depend  not  only  upon  the 
age  of  the  formation,  but  upon  the  number  of  times  which 
its  materials  have  been  broken  up,  and  the  periods  during 
which  they  have  remained  unmetamorphosed,  and  exposed  to 
the  action  of  infiltrating  waters The  proportion  be- 
tween the  alkalies  and  the  alumina  in  the  argillaceous  sedi- 
ments of  any  given  formation  is  not  therefore  in  direct  relation 
to  its  age ;  but  indicates  the  extent  to  which  these  sediments 
have  been  subjected  to  the  influences  of  water,  carbonic  acid, 
and  vegetation.  If,  however,  it  may  be  assumed  that  this 
action,  other  things  being  equal,  has  on  the  whole  been  pro- 
portionate to  the  newness  of  the  formation,  it  is  evident  that 
the  chemical  and  mineralogical  composition  of  different  systems 
of  rocks  must  vary  with  their  antiquity ;  and  it  now  remains 
to  find  in  their  comparative  study  a  guide  to  their  respective 
ages. 

It  will  be  evident  that  silicious  deposits  and  chemical  pre- 
cipitates, like  the  carbonates  and  silicates  of  lime  and  magnesia, 
may  exist  with  similar  characters  in  the  geological  formations 
of  any  age ;  not  only  forming  beds  apart,  but  mingled  with 
the  impermeable  silico-aluminous  sediments,  of  mechanical  ori- 
gin. Inasmuch  as  the  chemical  agencies  giving  rise  to  these 
compounds  were  then  most  active,  they  may  be  expected  in 
greatest  abundance  in  the  rocks  of  the  earlier  periods.  In  the 
case  of  the  permeable  and  more  highly  silicious  class  of  sedi- 
ments already  noticed,  whose  chief  elements  are  silica,  alumina, 
and  alkalies,  the  deposits  of  different  ages  will  be  marked 
chiefly  by  a  progressive  diminution  in  the  amount  of  potash 
and  more  especially  of  the  soda  which  they  contain.  In  the 
oldest  rocks  the  proportion  of  alkali  will  be  nearly  or  quite 
sufficient  to  form  orthoclase  and  albite  with  the  whole  of  the 
alumina  present;  but  as  the  alkali  diminishes,  a  portion  of 
the  alumina  will  crystallize,  on  the  metamorphism  of  the  sedi- 
ments, in  the  form  of  a  potash-mica,  such  as  muscovite  or 
margarodite.  While  the  oxygen-ratio  between  the  alumina 


28  THE  CHEMISTRY  OF  METAMORPHIC  ROCKS.  [III. 

and  the  alkali  in  the  feldspars  just  named  is  3  : 1,  it  becomes 
6  : 1  in  margarodite,  and  12  : 1  in  muscovite.  The  appearance 
of  these  micas  in  a  rock  denotes,  then,  a  diminution  in  the 
amount  of  alkali,  until  in  some  strata  the  feldspar  almost 
entirely  disappears,  and  the  rock  becomes  a  quartzose  mica- 
schist.  In  sediments  still  further  deprived  of  alkali,  metamor- 
phism  gives  rise  to  schists  filled  with  crystals  of  kyanite  or  of 
andalusite,  which  are  .simple  silicates  of  alumina,  into  whose 
composition  alkalies  do  not  enter;  or  in  case  the  sediment 
still  retains  oxide  of  iron,  staurolite  and  iron-alumina  garnet 
take  their  place.  The  matrix  of  all  of  these  minerals  is  gen- 
erally a  quartzose  mica-schist.  The  last  term  in  this  exhaustive 
process  appears  to  be  represented  by  the  disthene  and  pyrophyl- 
lite  rocks,  which  occur  in  some  regions  of  crystalline  schists. 

In  the  second  class  of  sediments  we  have  alumina  in  excess, 
with  a  small  proportion  of  silica,  and  a  deficiency  of  alkalies, 
besides  a  variable  proportion  of  silicates  or  carbonates  of  lime, 
magnesia,  and  oxide  of  iron.  The  result  of  the  processes  already 
described  will  produce  a  gradual  diminution  in  the  amount 
of  alkali,  which  is  chiefly  soda.  So  long  as  this  predominates, 
the  metamorphism  of  these  sediments  will  give  rise  to  feldspars 
like  oligoclase,  labradorite,  or  scapolite  (a  dimetric  feldspar) ; 
but  in  sediments'  where  lime  replaces  a  great  proportion  of  the 
soda,  there  appears  a  tendency  to  the  production  of  denser 
silicates,  like  lime-alumina  garnet,  and  epidote,  or  zoisite,  which 
replace  the  soda-lime  feldspars.  Minerals  like  the  chlorites, 
dichroite  and  chloritoid  are  formed  when  magnesia  and  iron 
replace  lime.  In  all  of  these  cases  the  excess  of  the  silicates 
of  earthy  protoxides  over  the  silicate  of  alumina  is  represented 
in  the  altered  strata  by  hornblende,  pyroxene,  olivine,  and 
similar  species ;  which  give  rise,  by  their  admixture  with  the 
double  aluminous  silicates,  to  diorite,  diabase,  euphotide,  eklo- 
gite,  and  similar  compound  rocks. 

In  eastern  North  America,  the  crystalline  strata,  so  far  as 
yet  studied,  may  be  conveniently  classed  in  five  groups,  corre- 
sponding to  as  many  different  geological  series,  four  of  which 
will  be  considered  in  the  present  paper. 


III.]  THE  CHEMISTRY  OF  METAMORPHIC  ROCKS.  29 

I.  The  Laurentian  system  represents  the  oldest  known  rocks 
of  the  globe,  and  is  supposed  to  be  the  equivalent  of  the  Primi- 
tive Gneiss  formation  of  Scandinavia,  and  that  of  the  Western 
Islands  of  Scotland,  to  which  also  the  name  of  Laurentian  is 
now  applied.     It  has  been  investigated  in  Canada   along   a 
continuous  outcrop  from  the  coast  of  Labrador  to  Lake  Su- 
perior, and  also  over  a  considerable  area  in  northern   !N"ew 
York. 

II.  Associated  with  this  system  is  a  series  of  strata  charac- 
terized by  a  great  development  of  anortholites,  of  which  the 
hypersthenite  or  opalescent  feldspar-rock  of  Labrador  may  be 
taken  as  a  type.     These  strata  overlie  the  Laurentian  gneiss, 
and  are  regarded  as  constituting  a  second  and  more  recent 
group  of  crystalline  rocks,  to  which  the  name  of  the  Labrador 
series   may  be   provisionally  given.      [Since   called   Xorian ; 
see  note  to  page  31.]     From  evidence  recently  obtained,  Sir 
William  Logan  conceives  it  probable  that  this  series  is  uncom- 
formable  with  the  older  Laurentian  system,  and  is  separated 
from  it  by  a  long  interval  of  time. 

III.  In  the  third  place  is  a  great  series  of  crystalline  schists 
(the  Green  Mountain  series),  which  are  in  Canada  referred  to 
the  Quebec  group,  an  inferior  part  of  the  Lower  Silurian  sys- 
tem.    They  appear  to  correspond  both  lithologically  and  strati- 
graphically  with  the  Schistose  group  of  the  Primitive  Slate 
formation  of  Xorway,  as  recognized  by  Naumann  and  Keilhau, 
and  to  be  there  represented  by  the  strata  in  the  vicinity  of 
Drontheim,  and  those  of  the  Dofrefeld.     The  Huronian  series 
of  Canada  in  like  manner  appears  to  correspond  to  the  Quart- 
zose  group  of  the  same  Primitive  Slate  formation.*     It  consists 
of  quartzites,  varieties  of  imperfect  gneiss,   diorites,   silicious 
and  feldspathic  schists  passing  into  argillites,  with  limestones, 

and  great  beds  of  hematite The  Huronian  series  is  as 

yet  but  imperfectly  studied,  and  for  the  present  will  not  be 
further  considered,  t 

*  See  Macfarlane,  —  Primitive  Formations  of  Norway  and  Canada  com- 
pared, —  Canadian  Naturalist,  VII.  113,  162. 
[  t  It  will  be  seen  above  that  I  have  indicated./^  groups  of  crystalline  rocks, 


30  THE   CHEMISTRY   OF  METAMOKPHIC   ROCKS.  [III. 

IV.  In  the  fourth  place  are  to  be  noticed  the  metamorphosed 
strata  of  Upper  Silurian  and  Devonian  age,  with  which  may 
also  be  included  those  of  the  Carboniferous  system  in  eastern 
New  England.  This  group  has  as  yet  been  imperfectly  stud- 
ied, but  presents  interesting  peculiarities. 

In  the  oldest  of  these,  the  Laurentian  system,  the  first  class 
of  aluminous  rocks  takes  the  form  of  granitoid  gneiss,  which 
is  often  coarse-grained  and  porphyritic.  Its  feldspar  is  fre- 
quently a  nearly  pure  potash-orthoclase,  but  sometimes  con- 
tains a  considerable  proportion  of  soda.  Mica  is  often  almost 
entirely  wanting,  and  is  never  abundant  in  any  large  mass  of 
this  gneiss,  although  small  bands  of  mica-schist  are  occasionally 
met  with.  Argillites,  which  from  their  general  predominance 
of  potash  and  silica  are  related  to  the  first  class  of  sediments, 
are,  so  far  as  known,  wanting  throughout  the  Laurentian 
series ;  nor  is  any  rock  here  met  with,  which  can  be  regarded 
as  derived  from  the  metamorphism  of  sediments  like  the  argil- 
lites  of  more  modern  series.  Chloritic  and  chiastolite-schists 
and  kyanite  are,  if  not  altogether  wanting,  extremely  rare  in 
the  Laurentian  system.  The  aluminous  sediments  of  the 
second  class  are,  however,  represented  in  this  system  by  a 
diabase  made  up  of  dark  green  pyroxene  and  bluish  labradorite, 
often  associated  with  a  red  alumino-ferrous  garnet.  This  latter 
mineral  also  sometimes  constitutes  small  beds,  often  with 
quartz,  and  occasionally  with  a  little  pyroxene.  These  basic 
aluminous  minerals  form,  however,  but  an  insignificant  part 
of  the  mass  of  strata.  This  system  is  further  remarkable  by 
the  small  amount  of  ferruginous  matter  diffused  through  the 
strata ;  from  which  the  greater  part  of  the  iron  seems  to  have 
been  removed,  and  accumulated  in  the  form  of  immense  beds 
of  hematite  and  magnetic  iron.  Beds  and  veins  of  crystalline 
plumbago  also  characterize  this  series,  and  are  generally  found 
with  the  limestones,  which  are  here  developed  to  an  extent 

while  attempting  to  describe  but  four  ;  the  fifth  being  the  Huronian  series, 
which  from  its  close  resemblance  to  the  third  series  (from  which  it  was  by 
Logan  regarded  as  geologically  distinct),  was  to  me  a  source  of  great  per- 
plexity. For  further  considerations  touching  this  question,  see  the  remarks 
on  page  18.] 


III.]  THE  CHEMISTRY  OF  METAMORPHIC  ROCKS.  31 

unknown  in  more  recent  formations,  and  are  associated  with 
veins  of  crystalline  apatite,  which  sometimes  attain  a  thick- 
ness of  several  feet.  The  serpentines  of  this  series,  so  far 
as  yet  studied  in  Canada,  are  generally  pale- colored,  and 
contain  an  unusual  amount  of  water,  a  small  proportion  of 
oxide  of  iron,  and  neither  chrome  nor  nickel ;  both  of  which 
are  almost  always  present  in  the  serpentines  of  the  third 
series.* 

The  second  or  Labrador  series  is  characterized,  as  already 
remarked,  by  the  predominance  of  great  beds  of  anortholite, 
composed  chiefly  of  triclinic  feldspars,  which  vary  in  compo- 
sition from  anorthite  to  andesine.  These  feldspars  sometimes 
form  mountain  masses,  almost  without  any  admixture,  but  at 
other  times  include  portions  of  pyroxene,  which  passes  into 
hypersthene.  Beds  of  nearly  pure  pyroxenite  are  met  with 
in  this  series,  and  others  which  would  be  called  hyperite  and 
diabase.  These  anortholite  rocks  are  frequently  compact,  but 
are  more  often  granitoid  in  structure.  They  are  generally 
grayish,  greenish,  or  bluish  in  color,  and  become  white  on  the 
weathered  surfaces.  The  opalescent  labradorite-rock  of  Labra- 
dor is  a  characteristic  variety  of  these  anortholites  ;  which 
often  contain  small  portions  of  red  garnet  and  brown  mica, 
and  more  rarely,  epidote,  olivine,  and  a  little  quartz.  They 
are  sometimes  slightly  calcareous.  Magnetic  iron  and  ilmenite 
are  often  disseminated  in  these  rocks,  and  occasionally  form 
masses  or  beds  of  considerable  size.  These  anortholites  con- 
stitute the  predominant  part  of  the  Labrador  series,  so  far  as 
yet  examined.  They  are,  however,  associated  with  beds  of 
quartzose  orthoclase-gneiss,  which  represent  the  first  class  of 
aluminous  sediments,  and  with  crystalline  limestones ;  and 
they  will  probably  be  found,  when  further  studied,  to  offer  a 
complete  lithological  series.  These  rocks  have  been  observed  in 
several  areas  among  the  Laurentide  Mountains,  from  the  coast 
of  Labrador  to  Lake  Huron,  and  are  also  met  with  among  the 

*  See  in  this  connection  the  author  on  the  History  of  Ophiolites,  Am. 
Jour.  Science  (2),  XXV.  117,  and  XXVI.  234. 


32  THE  CHEMISTRY  OF  METAMORPHIC  ROCKS.  [III. 

Adirondack  Mountains ;  of  which,  according  to  Emmons,  they 
form  the  highest  summits.* 

In  the  third  (or  Green  Mountain)  series,  which  we  have 
referred  to  the  Lower  Silurian  age,  the  gneiss  is  sometimes 
granitoid,  but  less  markedly  so  than  in  the  first;  and  it  is 
much  more  frequently  micaceous,  often  passing  into  micaceous 
schist,  a  common  variety  of  which  contains  disseminated  a 
large  quantity  of  chloritoid.  Argillites  abound,  and  under 
the  influence  of  metamorphism  sometimes  develop  crystalline 
orthoclase.  At  other  times  they  are  converted  into  a  soft 
micaceous  mineral,  and  form  a  kind  of  mica-schist.  Chias- 
tolite  and  staurolite  are  never  met  with  in  the  schists  of  this 
series,  at  least  in  its  northern  portions,  throughout  Canada  and 
New  England.  The  anortholites  of  the  Labrador  series  are 
here  represented  by  fine-grained  diorites,  in  which  the  feldspar 
varies  from  albite  to  very  basic  varieties,  which  are  sometimes 
associated  with  an  aluminous  mineral  allied  to  chlorite  in  com- 
position. Chloritic  schists,  frequently  accompanied  by  epidote, 
abound  in  this  series.  The  great  predominance  of  magnesia 
in  the  forms  of  dolomite,  magnesite,  steatite,  and  serpentine, 
is  also  characteristic  of  portions  of  this  series.  The  latter, 
which  forms  great  beds  (ophiolites),  is  marked  by  the  almost 
constant  presence  of  small  portions  of  the  oxides  of  chrome 
and  nickel.  These  metals  are  also  common  in  the  other  mag- 
nesian  rocks  of  the  series ;  green  chrome-garnets,  and  chrome- 
mica  occur;  and  beds  of  chromic  iron  ore  are  found  in  the 
ophiolites  of  the  series.  It  is  also  a  gold-bearing  formation 
in  eastern  North  America,  and  contains  large  quantities  of 

copper  ores  in  interstratified  beds The  only  graphite 

which  has  been  found  in  the  third  series  is  in  the  form  of 
impure  plumbaginous  shales. 

The  metamorphic  rocks  of  the  fourth  (or  White  Mountain) 
series,  as  seen  in  southeastern  Canada,  are  for  the  greater  part 
quartzose  and  micaceous  schists,  more  or  less  feldspathic; 
which  in  certain  portions  become  remarkable  for  a  great 

*  A  further  description  of  this  Labrador  or  Norian  series  is  given  in  Essay 
XIII. 


III.]  THE  CHEMISTRY  OF  MET&MORPHIC  ROCKS.  33 

development  of  crystals  of  staurolite  and  of  red  garnet.  A 
large  amount  of  argillite  occurs  in  this  series ;  and  when  al- 
tered, whether  locally  by  the  proximity  of  intrusive  rock,  or 
by  normal  metamorphism,  exhibits  a  micaceous  mineral,  and 
crystals  of  andalusite  ;  so  that  it  becomes  known  as  chiastolite- 
slate  in  parts  of  its  distribution.  Granitoid  gneiss  is  abundantly 

associated  with  these  crystalline  schists The  crystalline 

limestones  and  ophiolites  of  eastern  Massachusetts,  which  are 
probably  of  this  series,  resemble  those  of  the  Laurentian  sys- 
tem; and  the  coal  beds  in  that  region  are  in  some  parts 
changed  into  graphite.*  .... 

Large  masses  of  intrusive  granite  occur  among  the  crystalline 
strata  of  the  fourth  series,  but  the  so-called  granites  of  the 
Laurentian  appear  to  be  in  every  case  indigenous  rocks ;  that 
is  to  say,  strata  altered  in  situ,  and  still  retaining  evidences 
of  stratification.  The  same  thing  is  true  with  regard  to  the 
ophiolites  and  the  anortholites  of  both  series.  No  evidences 
of  the  hypothetical  granitic  substratum  are  met  with  in  the 
Laurentian  system,  although  this  is  in  one  district  penetrated 
by  great  masses  of  syenite,  orthophyre,  and  dolerite.  Granitic 
veins,  with  minerals  containing  the  rarer  elements,  such  as 
boron,  fluorine,  lithium,  zirconium,  and  glucinum,  are  met  with 
alike  in  the  oldest  and  the  newest  gneiss  in  North  America. 
These,  however,  I  regard  as  having  been  formed,  like  metal- 
liferous veins,  by  aqueous  deposition  in  fissures  in  the  strata. 

The  above  observations  upon  the  metamorphic  strata  of  a 
wide  region  seem  to  be  in  conformity  with  the  chemical  prin- 
ciples already  laid  down  in  this  paper ;  which  it  remains  for 
geologists  to  apply  to  the  rocks  of  other  regions,  and  thus 
determine  whether  they  are  susceptible  of  a  general  applica- 
tion. I  have  found  that  the  blue  crystalline  labradorite  of 
the  Labrador  series  of  Canada  is  exactly  represented  by  speci- 

[*  See  in  this  connection  the  prefatory  note  to  this  essay,  and  also  Essays 
XIII.  and  XV.  The  carboniferous  age  of  the  graphite  of  eastern  Massachu- 
setts has  been  generally  assumed  by  geologists,  though  without  any  good 
reason.  The  crystalline  rocks  of  this  region,  embracing  New  Hampshire  and 
eastern  Massachusetts,  include  representatives  of  the  second,  third,  and 
fourth,  and  probably  also  of  the  first  series.] 

2*  0 


34  THE   CHEMISTRY  OF  METAMORPHIC  ROCKS.  [III. 

mens  from  Scarvig,  in  Skye ;  and  the  ophiolites  of  lona  resem- 
ble those  of  the  Laurentian  series  in  Canada.  Many  of  the 
rocks  of  Donegal  appear  to  me  lithologically  identical  with 
those  of  the  Laurentian  period ;  while  the  serpentines  of  Agha- 
doey,  containing  chrome  and  nickel,  and  the  andalusite  and 
kyanite-schists  of  other  parts  of  Donegal,  cannot  be  distin- 
guished from  those  which  characterize  the  altered  palaeozoic 
strata  of  Canada.  It  is  to  remarked  that  chrome  and  nickel 
bearing  serpentines  are  met  with  in  the  same  geological  horizon 
in  Canada  and  Norway ;  and  that  those  of  the  Scottish  High- 
lands, which  contain  the  same  elements,  belong  to  the  newer 
gneiss  formation ;  which,  according  to  Sir  Roderick  Murchison, 
would  be  of  similar  age.*  The  serpentines  of  Cornwall,  the 
Vosges,  Mount  Eosa,  and  many  other  regions,  agree  in  contain- 
ing chrome  and  nickel ;  which,  on  the  other  hand,  seem  to  be 
absent  from  the  serpentines  of  the  Primitive  Gneiss  formation 
of  Scandinavia.  It  remains  to  be  determined  how  far  chemical 
and  mineralogical  differences,  such  as  those  which  have  been 
here  indicated,  are  geological  constants.  Meanwhile  it  is 
greatly  to  be  desired  that  future  chemical  and  mineralogical 
investigations  of  crystalline  rocks  should  be  made  with  this 
question  in  view;  and  that  the  metamorphic  strata  of  the 
British  Isles,  and  of  southern  and  central  Europe,  be  studied 
with  reference  to  the  important  problem  which  it  has  been 
my  endeavor,  in  the  present  paper,  to  lay  before  the  Society. 

*  See  in  this  connection  the  Essays  XIII.  and  XV. 


IV. 


THE   CHEMISTRY  OF  THE   PRIMEVAL 
EARTH. 

(1867.) 

The  following  paper  is  an  abstract  of  a  Friday-evening  lecture,  given  before  the 
Royal  Institution  of  Great  Britain,  London,  May  31,  1867,  and  here  reprinted  from  the 
Proceedings  of  the  Institution.  As  an  attempt  to  bring  together  in  a  connected  form 
some  of  the  latest  conclusions  of  chemical  and  geological  science,  it  attracted  at  the 
time  considerable  attention,  having  been  frequently  reprinted,  several  times  translated, 
and  adversely  criticised  both  in  the  Chemical  News  and  the  Geological  Magazine.  My 
replies  to  these  criticisms  the  reader  will  find  in  these  same  journals  for  February,  1868. 

As  bearing  upon  the  subject  of  the  lecture,  an  Appendix  is  subjoined  including  a  note 
on  the  relation  of  the  atmosphere  of  early  times  to  climate,  and  to  the  temperature 
near  the  sea-level.     For  further  discussion  upon  the  origin  and  mode  of  formation  of 
dolomites  and  gypsum,  and  their  relation  to  the  composition  of  the  atmosphere,  the . 
reader  is  referred  to  Paper  VIII.  in  this  volume. 

THE  natural  history  of  our  planet,  to  which  we  give  the  name 
of  geology,  is  necessarily  a  very  complex  science,  including,  as 
it  does,  the  concrete  sciences  of  mineralogy,  "botany,  and  zoology, 
and  the  abstract  sciences,  chemistry  and  physics.  These  latter 
sustain  a  necessary  and  very  important  relation  to  the  whole 
process  of  development  of  our  earth  from  its  earliest  ages,  and 
we  find  that  the  same  chemical  laws  which  have  presided  over 
its  changes  apply  also  to  those  of  extra-terrestrial  matter.  Re- 
cent investigations  show  the  presence  in  the  sun,  and  even  in 
the  fixed  stars,  —  suns  of  other  systems,  —  the  same  chemical 
elements  as  in  our  own  planet.  The  spectroscope,  that  marvel- 
lous instrument,  has,  in  the  hands  of  modern  investigators, 
thrown  new  light  upon  the  composition  of  the  farthest  bodies 
of  the  universe,  and  has  made  clear  many  points  which  the 
telescope  was  impotent  to  resolve.  The  results  of  extra-terres- 
trial spectroscopic  research  have  lately  been  set  forth  in  an 
admirable  manner  by  one  of  its  most  successful  students,  Mr. 


36     THE  CHEMISTRY  OF  THE  PRIMEVAL  EARTH.    [IV. 

Huggins.  WQ  see,  by  its  aid,  mattter  in  all  its  stages,  and 
trace  the  process  of  condensation  and  the  formation  of  worlds. 
It  is  long  since  Herschel,  the  first  of  his  illustrious  name,  con- 
ceived the  nebulae,  which  his  telescope  could  not  resolve,  to  be 
the  uncondensed  matter  from  which  worlds  are  made.  Sub- 
sequent astronomers,  with  more  powerful  glasses,  were  able  to 
show  that  many  of  these  nebula  are  really  groups  of  stars,  and 
thus  a  doubt  was  thrown  over  the  existence  of  nebulous  lumi- 
nous matter  in  space ;  but  the  spectroscope  has  now  placed 
the  matter  beyond  doubt.  By  its  aid,  we  find  in  the  heavens, 
planets,  bodies  like  our  earth,  shining  only  by  reflected  light ; 
suns,  self-luminous,  radiating  light  from  solid  matter ;  and, 
moreover,  true  nebulae,  or  masses  of  luminous  gaseous  matter. 
These  three  forms  represent  three  distinct  phases  in  the  con- 
densation of  the  primeval  matter  from  which  our  own  and 
other  planetary  systems  have  been  formed.  . 

This  nebulous  matter  is  conceived  to  be  so  intensely  heated 
as  to  be  in  the  state  of  true  gas  or  vapor,  and,  for  this  reason, 
feebly  luminous  when  compared  with  the  sun.  It  would  be 
out  of  place,  on  the  present  occasion,  to  discuss  the  detailed  re- 
sults of  spectroscopic  investigation,  or  the  beautiful  and  ingen- 
ious methods  by  which  modern  science  has  shown  the  existence 
in  the  sun,  and  in  many  other  luminous  bodies  in  space,  of  the 
same  chemical  elements  that  are  met  with  in  our  earth,  and 
even  in  our  own  bodies. 

Calculations  based  on  the  amount  of  light  and  heat  radiated 
from  the  sun  show  that  the  temperature  which  reigns  at  its  sur- 
face is  so  great  that  we  can  hardly  form  an  adequate  idea  of 
it.  Of  the  chemical  relations  of  such  intensely  heated  matter, 
modern  chemistry  has  made  known  to  us  some  curious  facts, 
which  help  to  throw  light  on  the  constitution  and  luminosity 
of  the  sun.  Heat,  under  ordinary  conditions,  is  favorable  to 
chemical  combination,  but  a  higher  temperature  reverses  all 
affinities.  Thus,  the  so-called  noble  metals,  gold,  silver,  mer- 
cury, etc.,  unite  with  oxygen  and  other  elements ;  but  these 
compounds  are  decomposed  by  heat,  and  the  pure  metals  are 
regenerated.  A  similar  reaction  was  many  years  since  shown 


IV.]  THE  CHEMISTRY  OF  THE  PRIMEVAL  EARTH.  37 

by  Mr.  Grove  with  regard  to  water,  whose  elements,  —  oxygen 
and  hydrogen,  —  when  mingled  and  kindled  by  flame,  or  by 
the  electric  spark,  unite  to  form  water,  which,  however,  at  a 
much  higher  temperature,  is  again  resolved  into  its  component 
gases.  Hence,  if  we  had  these  two  gases  existing  in  admixture 
at  a  very  high  temperature,  cold  would  actually  effect  their 
combination  precisely  as  heat  would  do  if  the  mixed  gases  were 
at  the  ordinary  temperature,  and  literally  it  would  be  found 
that  "  frost  performs  the  effect  of  fire."  The  recent  researches 
of  Henry  Ste.-Claire  Deville  and  others  go  far  to  show  that  this 
breaking  up  of  compounds,  or  dissociation  of  elements  by  in- 
tense heat,  is  a  principle  of  universal  application ;  so  that  we 
may  suppose  that  all  the  elements  which  make  up  the  sun  or 
our  planet  would,  when  so  intensely  heated  as  to  be  in  that 
gaseous  condition  which  all  matter  is  capable  of  assuming,  re- 
main uncombined,  —  that  is  to  say,  would  exist  together  in  the 
condition  of  what  we  call  chemical  elements,  whose  further  dis- 
sociation in  stellar  or  nebulous  masses  may  even  give  us  evidence 
of  matter  still  more  elemental  than  that  revealed  by  the  experi- 
ments of  the  laboratory,  where  we  can  only  conjecture  the  com- 
pound nature  of  many  of  the  so-called  elementary  substances. 

The  sun,  then,  is  to  be  conceived  as  an  immense  mass  of 
intensely  heated  gaseous  and  dissociated  matter,  so  condensed, 
however,  that,  notwithstanding  its  excessive  temperature,  it  has 
a  specific  gravity  not  much  below  that  of  water ;  probably 
offering  a  condition  analogous  to  that  which  Cagniard  de  la 
Tour  observed  for  volatile  bodies  when  submitted  to  great  press- 
ure at  temperatures  much  above  their  boiling  point.  The  radi- 
ation of  heat  going  on  from  the  surface  of  such  an  intensely 
heated  mass  of  uncombined  gases  will  produce  a  superficial 
cooling,  permitting  the  combination  of  certain  elements  and 
the  production  of  solid  or  liquid  particles,  which,  suspended 
in  the  still  dissociated  vapors,  become  intensely  luminous  and 
form  the  solar  photosphere.  The  condensed  particles,  carried 
down  into  the  intensely  heated  mass,  again  meet  with  a  heat 
of  dissociation ;  so  that  the  process  of  combination  at  the  sur- 
face is  incessantly  renewed,  while  the  heat  of  the  sun  may  be 


38      THE  CHEMISTKY  OF  THE  PRIMEVAL  EARTH.     [IV. 

supposed  to  be  maintained  by  the  slow  condensation  of  its  mass ; 
a  diminution  by  ToV otn  °f  ^ts  present  diameter  being  sufficient, 
according  to  Helmholtz,  to  maintain  the  present  supply  of  heat 
for  21,000  years. 

This  hypothesis  of  the  nature  of  the  sun  and  of  the  luminous 
process  going  on  at  its  surface  is  the  one  lately  put  forward  by 
Faye,  and,  although  it  has  met  with  opposition,  appears  to  be 
that  which  accords  best  with  our  present  knowledge  of  the 
chemical  and  physical  conditions  of  matter  such  as  we  must 
suppose  it  to  exist  in  the  condensing  gaseous  mass,  which, 
according  to  the  nebular  hypothesis,  should  form  the  centre 
of  our  solar  system.  Taking  this,  as  we  have  already  done,  for 
granted,  it  matters  little  whether  we  imagine  the  different 
planets  to  have  been  successively  detached  as  rings  during  the 
rotation  of  the  primal  mass,  as  is  generally  conceived,  or 
whether  we  admit  with  Chacornac  a  process  of  aggregation  or 
concretion  operating  within  the  primal  nebular  mass,  resulting 
in  the  production  of  sun  and  planets.  In  either  case  we  come 
to  the  conclusion  that  our  earth  must  at  one  time  have  been  in 
an  intensely  heated  gaseous  condition,  such  as  the  sun  now  pre- 
sents, self-luminous,  and  with  a  process  of  condensation  going 
on  at  first  at  the  surface  only,  until  by  cooling  it  must  have 
reached  the  point  where  the  gaseous  centre  was  exchanged  for 
one  of  combined  and  liquefied  matter. 

Here  commences  the  chemistry  of  the  earth,  to  the  discussion 
of  which  the  foregoing  considerations  have  been  only  prelim- 
inary. So  long  as  the  gaseous  condition  of  the  earth  lasted, 
we  may  suppose  the  whole  mass  to  have  been  homogeneous ; 
but  when  the  temperature  became  so  reduced  that  the  existence 
of  chemical  compounds  at  the  centre  became  possible,  those 
which  were  most  stable  at  the  elevated  temperature  then  pre- 
vailing would  be  first  formed.  Thus,  for  example,  while  com- 
pounds of  oxygen  with  mercury,  or  even  with  hydrogen,  could 
not  exist,  oxides  of  silicon,  aluminum,  calcium,  magnesium,  and 
iron  might  be  formed  and  condense  in  a  liquid  form  at  the 
centre  of  the  globe.  By  progressive  cooling,  still  other  elements 
would  be  removed  from  the  gaseous  mass,  which  would  form 


IV.]     THE  CHEMISTRY  OF  THE  PRIMEVAL  EARTH.     39 

the  atmosphere  of  the  non-gaseous  nucleus.  "We  may  suppose 
an  arrangement  of  the  condensed  matters  at  the  centre  accord- 
ing to  their  respective  specific  gravities,  and  thus  the  fact  that 
the  density  of  the  earth  as  a  whole  is  about  twice  the  mean 
density  of  the  matters  which  form  its  solid  surface  may  be 
explained.  Metallic-  or  metalloidal  compounds  of  elements, 
grouped  differently  from  any  compounds  known  to  us,  and  far 
more  dense,  may  exist  in  the  centre  of  the  earth. 

The  process  of  combination  and  cooling  having  gone  on  until 
those  elements  which  are  not  volatile  in  the  heat  of  our  ordinary 
furnaces  were  condensed  into  a  liquid  form,  we  may  here  in- 
quire what  would  be  the  result,  upon  the  mass,  of  a  further 
reduction  of  temperature.  It  is  generally  assumed  that  in 
the  cooling  of  a  liquid  globe  of  mineral  matter,  congelation 
would  commence  at  the  surface,  as  in  the  case  of  water ;  but 
water  offers  an  exception  to  most  other  liquids,  inasmuch  as  it 
is  denser  in  the  liquid  than  in  the  solid  form.  Hence,  ice  floats 
on  water,  and  freezing  water  becomes  covered  with  a  layer  of 
ice,  which  protects  the  liquid  below.  With  most  other  matters, 
however,  and  notably  with  the  various  mineral  and  earthy  com- 
pounds analogous  to  those  which  may  be  supposed  to  have 
formed  the  fiery-fluid  earth,  numerous  and  careful  experiments 
show  that  the  products  of  solidification  are  much  denser  than 
the  liquid  mass  ;  so  that  solidification  would  have  commenced 
at  the  centre,  whose  temperature  would  thus  be  the  congealing 
point  of  these  liquid  compounds.  The  important  researches 
of  Hopkins  and  Fairbairn  on  the  influence  of  pressure  in  aug- 
menting the  melting  point  of  such  compounds  as  contract  in 
solidifying  are  to  be  considered  in  this  connection. 

It  is  with  the  superficial  portions  of  the  fused  mineral  mass 
of  the  globe  that  we  have  now  to  do  ;  since  there  is  no  good 
reason  for  supposing  that  the  deeply  seated  portions  have  in- 
tervened in  any  direct  manner  in  the  production  of  the  rocks 
which  form  the  superficial  crust.  This,  at  the  time  of  its  first 
solidification,  presented  probably  an  irregular,  diversified  sur- 
face from  the  result  of  contraction  of  the  congealing  mass,  which 
at  last  formed  a  liquid  bath  of  no  great  depth,  surrounding 


40     THE  CHEMISTRY  OF  THE  PRIMEVAL  EARTH.     [IV. 

the  solid  nucleus.  It  is  to  the  composition  of  this  crust  that 
we  must  direct  our  attention,  since  therein  would  be  found  all 
the  elements  (with  the  exception  of  such  as  were  still  in  the 
gaseous  form)  now  met  with  in  the  known  rocks  of  the  earth. 
This  crust  is  now  everywhere  buried  beneath  its  own  ruins, 
and  we  can  only  from  chemical  considerations  attempt  to  re- 
construct it.  If  we  consider  the  conditions  through  which  it 
has  passed,  and  the  chemical  affinities  which  must  have  come 
into  play,  we  shall  see  that  they  are  just  what  would  now  result 
if  the  solid  land,  sea,  and  air  were  made  to  react  upon  each 
other  under  the  influence  of  intense  heat.  To  the  chemist  it  is 
at  once  evident  that  from  this  would  result  the  conversion  of 
all  carbonates,  chlorides,  and  sulphates  into  silicates,  and  the 
separation  of  the  carbon,  chlorine,  and  sulphur  in  the  form  of 
acid  gases,  which,  with  nitrogen,  watery  vapor,  and  a  probable 
excess  of  oxygen,  would  form  the  dense  primeval  atmosphere. 
The  resulting  fused  mass  would  contain  all  the  bases  as  silicates, 
and  must  have  much  resembled  in  composition  certain  furnace- 
slags  or  volcanic  glasses.  The  atmosphere,  charged  with  acid 
gases,  which  surrounded  this  primitive  rock,  must  have  been  of 
immense  density.  Under  the  pressure  of  such  a  high  baromet- 
ric column,  condensation  would  take  place  at  a  temperature 
much  above  the  present  boiling  point  of  water,  and  the  de- 
pressed portions  of  the  half-cooled  crust  would  be  flooded  with 
a  highly  heated  solution  of  hydrochloric  and  sulphuric  acids, 
whose  action  in  decomposing  the  silicates  is  easily  intelligible 
to  the  chemist.  The  formation  of  chlorides  and  sulphates  of  the 
various  bases,  and  the  separation  of  silica,  would  go  on  until 
the  affinities  of  the  acids  were  satisfied,  and  there  would  be  a 
separation  of  silica,  taking  the  form  of  quartz,  and  the  produc- 
tion of  a  sea- water  holding  in  solution,  besides  the  chlorides  and 
sulphates  of  sodium,  calcium,  and  magnesium,  salts  of  alumi- 
num and  other  metallic  bases.  The  atmosphere,  being  thus 
deprived  of  its  volatile  chlorine  and  sulphur  compounds,  would 
approximate  to  that  of  our  own  time,  but  differ  in  its  greater 
amount  of  carbonic  acid. 

We  next  enter  into  the  second  phase  in  the  action  of  the 


IV.]    THE  CHEMISTRY  OF  THE  PRIMEVAL  EARTH.     41 

atmosphere  upon  the  earth's  crust.  This,  unlike  the  first, 
which  was  subaqueous,  or  operative  only  on  the  portion  cov- 
ered with  the  precipitated  water,  is  subaerial,  and  consists  in  the 
decomposition  of  the  exposed  parts  of  the  primitive  crust  under 
the  influence  of  the  carbonic  acid  and  moisture  of  the  air,  which 
convert  the  .complex  silicates  of  the  crust  into  a  silicate  of 
alumina,  or  clay;  while  the  separated  lime,  magnesia,  and 
alkalies,  being  converted  into  carbonates,  are  carried  down 
into  the  sea  in  a  state  of  solution. 

The  first  effect  of  these  dissolved  carbonates  would  be  to 
precipitate  the  dissolved  alumina  and  the  heavy  metals,  after 
which  would  result  a  decomposition  of  the  chloride  of  calcium 
of  the  sea-water,  resulting  in  the  production  of  carbonate  of 
lime  or  limestone,  and  chloride  of  sodium  or  common  salt.  This 
process  is  one  still  going  on  at  the  earth's  surface,  slowly 
breaking  down  and  destroying  the  hardest  rocks,  and,  aided  by 
mechanical  processes,  transforming  them  into  clays ;  although 
the  action,  from  the  comparative  rarity  of  carbonic  acid  in  the 
atmosphere,  is  far  less  energetic  than  in  earlier  times,  when  the 
abundance  of  this  gas,  and  a  higher  temperature,  favored  the 
•  chemical  decomposition  of  the  rocks.  But  now,  as  then,  every 
clod  of  clay  formed  from  the  decay  of  a  crystalline  rock  cor- 
responded to  an  equivalent  of  carbonic  acid  abstracted  from  the 
atmosphere,  and  to  equivalents  of  carbonate  of  lime  and  com- 
mon salt  formed  from  the  chloride  of  calcium  of  the  sea-water. 

It  is  very  instructive,  in  this  connection,  to  compare  the 
composition  of  the  waters  of  the  modern  ocean  with  that  of 
the  sea  in  ancient  times,  whose  composition  we  learn  from  the 
fossil  sea-waters  which  are  still  to  be  found  in  certain  regions, 
imprisoned  in  the  pores  of  the  older  stratified  rocks.  These 
are  vastly  richer  in  salts  of  lime  and  magnesia  than  those  of 
the  present  sea,  from  which  have  been  separated,  by  chemical 
processes,  all  the  carbonate  of  lime  of  our  limestones,  with 
the  exception  of  that  derived  from  the  subaerial  decay  of  cal- 
careous and  magnesian  silicates  belonging  to  the  primitive  crust. 

The  gradual  removal,  in  the  form  of  carbonate  of  lime,  of  the 
carbonic  acid  from  the  primeval  atmosphere,  has  been  connected 


42     THE  CHEMISTRY  OF  THE  PRIMEVAL  EARTH.     [IV. 

with  great  changes  in  the  organic  life  of  the  globe.  The  air 
was  doubtless  at  first  unfit  for  the  respiration  of  warm-blooded 
animals,  and  we  find  the  higher  forms  of  life  coming  gradually 
into  existence  as  we  approach  the  present  period  of  a  purer  air. 
Calculations  lead  us  to  conclude  that  the  amount  of  carbon 
thus  removed  in  the  form  of  carbonic  acid  has  been  so  enor- 
mous, that  we  must  suppose  the  earlier  forms  of  air-breathing 
animals  to  have  been  peculiarly  adapted  to  live  in  an  atmos- 
phere which  would  probably  be  too  impure  to  support  modem 
reptilian  life.  The  agency  of  plants  in  purifying  the  primitive 
atmosphere  was  long  since  pointed  out  by  Brongniart,  and  our 
great  stores  of  fossil  fuel  have  been  derived  from  the  decompo- 
sition, by  the  ancient  vegetation,  of  the  excess  of  carbonic  acid 
of  the  early  atmosphere,  which  through  this  agency  was  ex- 
changed for  oxygen  gas.  In  this  connection  the  vegetation  of 
former  periods  presents  the  curious  phenomenon  of  plants  allied 
to  those  now  growing  beneath  the  tropics  flourishing  within 
the  polar  circles.  Many  ingenious  hypotheses  have  been  pro- 
posed to  account  for  the  warmer  climate  of  earlier  times,  but 
are  at  best  unsatisfactory,  and  it  appears  to  me  that  the  true 
solution* of  the  problem  maybe  found  in  the  constitution  of  the' 
early  atmosphere,  when  considered  in  the  light  of  Dr.  Tyndall's 
beautiful  researches  on  radiant  heat.  He  has  found  that  the 
presence  of  a  few  hundredths  of  carbonic-acid  gas  in  the  atmos- 
phere, while  offering  almost  no  obstacle  to  the  passage  of  the 
solar  rays,  would  suffice  to  prevent  almost  entirely  the  loss,  by 
radiation,  of  obscure  heat,  so  that  the  surface  of  the  land  be- 
neath such  an  atmosphere  would  become  like  a  vast  orchard- 
house,  in  which  the  conditions  of  climate  necessary  to  a  luxu- 
riant vegetation  would  be  extended  even  to  the  polar  regions. 

This  peculiar  condition  of  the  early  atmosphere  cannot  fail  to 
have  influenced  in  many  other  ways  the  processes  going  on  at 
the  earth's  surface.*  To  take  a  single  example  :  one  of  the 
processes  by  which  gypsum  may  be  produced  at  the  earth's 
surface  involves  the  simultaneous  production  of  bicarbonate  of 
magnesia.  This,  being  more  soluble  than  the  gypsum,  is  not 

*  See  Append! £  to  this  paper. 


IV.]     THE  CHEMISTRY  OF  THE  PRIMEVAL  EARTH.     43 

always  now  found  associated  with  it ;  but  we  have  indirect 
evidence  that  it  was  formed  and  subsequently  carried  away,  in 
the  case  of  many  gypsum  deposits,  whose  thickness  indicates  a 
long  continuance  of  the  process  under  conditions  much  more 
perfect  and  complete  than  we  can  attain  under  our  present 
atmosphere.  While  studying  this  reaction  I  was  led  to  inquire 
whether  the  carbonic  acid  of  the  earlier  periods  might  not  have 
favored  the  formation  of  gypsum ;  and  I  found,  by  repeating 
the  experiments  in  an  artificial  atmosphere  impregnated  with 
carbonic  acid,  that  such  was  really  the  case.*  We  may  thence 
conclude  that  the  peculiar  composition  of  the  primeval  atmos- 
phere was  the  essential  condition  under  which  the  great  deposits 
of  gypsum,  generally  associated  with  inagnesian  limestones, 
were  formed. 

The  reactions  of  the  atmosphere,  which  we  have  considered, 
would  have  the  effect  of  breaking  down  and  disintegrating  the 
surface  of  the  primeval  globe,  covering  it  everywhere  with  beds 
of  stratified  rock  of  mechanical  or  of  chemical  origin.  These 
now  so  deeply  cover  the  partially  cooled  surface  that  the  amount 
of  heat  escaping  from  below  is  inconsiderable,  although  in 
earlier  times  it  was  very  much  greater,  and  the  increase  of  tem- 
perature met  with  in  descending  into  the  earth  must  then  have 
been  many  times  more  rapid  than  now.  The  effect  of  this 
heat  upon  the  buried  sediments  would  be  to  soften  them,  pro- 
ducing new  chemical  reactions  between  their  elements,  and 
converting  them  into  what  are  known  as  crystalline  or  meta- 
morphic  rocks,  such  as  gneiss,  greenstone,  granite,  etc.  We  are 
often  told  that  granite  is  the  primitive  rock  or  substratum  of  the 
earth ;  but  this  is  not  only  unproved,  but  extremely  improbable. 
As  I  endeavored  to  show  in  the  early  part  of  this  discourse, 
the  composition  of  this  primitive  rock,  now  everywhere  hidden, 
must  have  been  very  much  like  that  of  a  slag  or  lava ;  and 
there  are  excellent  chemical  reasons  for  maintaining  that  granite 
is  in  every  case  a  rock  of  sedimentary  origin,  —  that  is  to  say, 
it  is  made  up  of  materials  which  were  deposited  from  water, 
like  beds  of  modern  sand  and  gravel,  and  includes  in  its  coin- 
*  See  Paper  VIII. 


44     THE  CHEMISTRY  OF  THE  PRIMEVAL  EARTH.     [IV. 

position  quartz,  which,  so  far  as  we  know,  can  only  be  gener- 
ated by  aqueous  agencies,  and  at  comparatively  low  tem- 
peratures. 

The  action  of  heat  upon  many  buried  sedimentary  rocks, 
however,  not  only  softens  or  melts  them,  but  gives  rise  to  a 
great  disengagement  of  gases,  such  as  carbonic  and  hydrochlo- 
ric acids,  and  sulphur  compounds,  all  of  which  are  results  of  the 
reaction  of  the  elements  of  sedimentary  rocks,  heated  in  pres- 
ence of  the  water  which  everywhere  filled  their  pores.  In  the 
products  thus  generated  we  have  a  rational  explanation  of  the 
chemical  phenomena  of  volcanoes,  which  are  vents  through 
which  these  fused  rocks  and  confined  gases  find  their  way  to  the 
surface  of  the  earth.  In  some  cases,  as  where  there  is  no  dis- 
engagement of  gases,  the  fused  or  half-fused  rocks  solidify  in 
situ,  or  in  rents  or  fissures  in  the  overlying  strata,  and  constitute 
eruptive  or  plutonic  rocks,  such  as  granite  and  basalt. 

This  theory  of  volcanic  phenomena  was  put  forward  in  germ 
by  Sir  John  F.  W.  Herschel  thirty  years  since,  and,  as  I  have 
during  the  past  few  years  endeavored  to  show,  it  is  the  one 
most  in  accordance  with  what  we  know  both  of  the  chemistry 
-and  the  physics  of  the  earth.  That  all  volcanic  and  plutonic 
phenomena  have  their  seat  in  the  deeply  buried  and  softened 
zone  of  sedimentary  deposits  of  the  earth,  and  not  in  its  primi- 
tive nucleus,  accords  with  the  conclusions  already  arrived  at 
relative  to  the  solidity  of  that  nucleus ;  with  the  geological 
relations  of  these  phenomena,  as  I  have  elsewhere  shown ;  and 
also  with  the  remarkable  mathematical  and  astronomical  de- 
ductions of  the  late  Mr.  Hopkins  of  Cambridge,  based  upon  the 
phenomena  of  precession  and  nutation,  those  of  Archdeacon 
Pratt,  and  those  of  Professor  Thompson  on  the  theory  of  the 
tides,  —  all  of  which  lead  to  the  same  conclusion,  namely, 
that  the  earth,  if  not  solid  to  the  centre,  must  have  a  crust  sev- 
eral hundred  miles  in  thickness,  which  would  practically  ex- 
clude it  from  any  participation  in  the  plutonic  phenomena  of 
the  earth's  surface,  except  such  as  would  result  from  its  high 
temperature  communicated  by  conduction  to  the  sedimentary 
strata  reposing  upon  it. 


IV.]    THE  CHEMISTRY  OF  THE  PRIMEVAL  EARTH.     45 

The  old  question  between  the  plutonists  and  the  neptunists, 
which  divided  the  scientific  world  in  the  last  generation,  was, 
in  brief,  this  :  whether  fire  or  water  has  been  the  great  agent 
in  giving  origin  and  form  to  the  rocks  of  the  earth's  crust. 
"While  some  maintained  the  direct  igneous  origin  of  such  rocks 
as  gneiss,  mica-schist,  and  serpentine,  and  ascribed  to  fire  the 
filling  of  metallic  veins,  others  —  the  neptunian  school  —  were 
disposed  to  shut  their  eyes  to  the  evidences  of  igneous  action 
on  the  earth,  and  even  sought  to  derive  all  rocks  from  a  primal 
aqueous  magma.  In  the  light  of  the  exposition  which  I  have 
laid  before  you  this  evening,  we  can,  I  think,  render  justice  to 
both  of  these  opposing  schools.  We  have  seen  how  reactions 
dependent  on  water  and  acid  solutions  have  transformed  the 
primitive  plutonic  mass,  and  how  the  resulting  aqueous  sedi- 
ments, when  deeply  buried,  come  again  within  the  domain  of 
fire,  to  be  transformed  into  crystalline  and  so-called  plutonic 
or  volcanic  rocks. 

The  scheme  which  I  have  thus  sought  to  put  before  you  in 
the  short  time  allotted  this  evening  is,  as  I  have  endeavored  to 
show,  in  strict  conformity  with  known  chemical  laws  and  the 
facts  of  physical  and  geological  science.  Did  time  permit,  I 
would  gladly  have  attempted  to  demonstrate  at  greater  length  its 
adaptation  to  the  explanation  of  the  origin  of  the  various  classes 
of  rocks,  of  metallic  veins  and  deposits,  of  mineral  springs,  and 
of  gaseous  exhalations.  I  shall  not,  however,  have  failed  in 
my  object,  if,  in  the  hour  which  we  have  spent  together,  I 
shall  have  succeeded  in  showing  that  chemistry  is  able  to 
throw  a  great  light  upon  the  history  of  the  formation  of  our 
globe,  and  to  explain  in  a  satisfactory  manner  some  of  the 
most  difficult  problems  of  geology ;  and  I  feel  that  there  is  a 
peculiar  fitness  in  bringing  such  an  exposition  before  the  mem- 
bers of  this  Royal  Institution,  which  has  been  for  so  many 
years  devoted  to  the  study  of  pure  science,  and  whose  glory  it 
is,  through  the  illustrious  men  who  have  filled,  and  those  who 
now  fill,  its  professorial  chairs,  to  have  contributed  more  than 
any  other  school  in  the  world  to  the  progress  of  modern  chem- 
istry and  physics. 


46     THE  CHEMISTRY  OF  THE  PRIMEVAL  EARTH.     [IV. 


APPENDIX. 

ON  THE   CLIMATE  OF  THE  EARTH  IN  FORMER  GEOLOGICAL 

PERIODS. 

The  following  note  appeared  in  the  London,  Edinburgh,  and  Dublin  Philosophical 
Magazine  for  October,  1863.  I  subsequently  found  that  this  consequence  of  his  dis- 
coveries had  not  escaped  Tyndall,  who,  in  his  Bakerian  lecture  for  1861  (Ibid.,  October, 
1861),  after  showing  that  from  its  influence  on  terrestrial  radiation  all  variation  in  the 
amount  of  aqueous  vapor  must  produce  changes  in  climate,  added,  "Similar  remarks 
would  apply  to  the  carbonic  acid  diffused  through  the  air,  while  an  almost  inappre- 
ciable admixture  of  any  of  the  hydro-carbon  vapors  would  produce  great  effects  on 
the  terrestrial  rays,  and  corresponding  changes  in  climate.  It  is  not  therefore  neces- 
sary to  assume  alterations  in  the  density  and  height  of  the  atmosphere,  to  account  for 
different  amounts  of  heat  being  preserved  to  the  earth  at  different  times ;  a  slight 
change  in  its  variable  constituents  would  account  for  this.  Such  changes,  in  fact, 
may  have  produced  all  the  mutations  of  climate  which  the  researches  of  geologists 
reveal."  A  letter  from  the  author  to  Dr.  Tyndall,  in  which  this  passage  was  cited, 
appeared  in  the  above-named  magazine  for  March,  1864. 

THE  late  researches  of  Dr.  John  Tyndall  on  the  relation  of  gases 
and  vapors  to  radiant  heat  are  important  in  their  bearing  upon  the 
temperature  of  the  earth's  surface  in  former  geological  periods.  He 
has  shown  that  heat,  from  whatever  source,  passes  through  hydro- 
gen, oxygen,  and  nitrogen  gases,  or  through  dry  air,  with  nearly  the 
same  facility  as  through  a  vacuum.  These  gases  are  thus  to  radiant 
heat  what  rock-salt  is  among  solids.  Glass,  and  some  other  solid 
substances  which  are  readily  permeable  to  light  and  to  solar  heat, 
offer,  as  is  well  known,  great  obstacles  to  the  passage  of  radiant  heat 
from  non-luminous  bodies  ;  and  Tyndall  has  recently  shown  that 
many  colorless  vapors  and  gases  have  a  similar  effect,  intercepting 
the  heat  from  such  sources,  by  which  they  become  warmed  and  in 
their  turn  radiate  heat.  Thus,  while  for  a  vacuum  the  absorption 
of  heat  from  a  body  at  212°  F.  is  represented  by  0,  and  that  for  dry 
air  is  1,  the  absorption  by  an  atmosphere  of  carbonic-acid  gas  equals 
90,  by  marsh  gas  403,  by  olefiant  gas  970,  and  by  ammonia  1,195. 
The  diffusion  of  olefiant  gas  of  one-inch  tension  in  a  vacuum  pro- 
duces an  absorption  of  90,  and  the  same  amount  of  carbonic-acid 
gas  an  absorption  of  5.6.  The  small  quantities  of  ozone  present  in 
electrolytic  oxygen  were  found  to  raise  its  absorptive  power  from  1 
to  85,  and  even  to  136  ;  and  the  watery  vapor  present  in  the  air  at 
ordinary  temperatures  in  like  manner  produces  an  absorption  of 
heat  represented  by  70  or  80.  Air  saturated  with  moisture  at  the 


IV.]          THE   CHEMISTRY  OF  THE  PRIMEVAL  EARTH.  47 

ordinary  temperature  absorbs  more  than  five  hundredths  of  the  heat 
radiated  from  a  metallic  vessel  filled  with  boiling  water,  and  Tyndall 
calculates  that  of  the  heat  radiated  from  the  earth's  surface  warmed 
by  the  sun's  rays,  one  tenth  is  intercepted  by  the  aqueous  vapor 
within  ten  feet  of  the  surface.  Hence  the  powerful  influence  of 
moist  air  upon  the  climate  of  the  globe.  Like  a  covering  of  glass, 
it  allows  the  sun's  rays  to  reach  the  earth,  but  prevents  to  a  great 
extent  the  loss  by  radiation  of  the  heat  thus  communicated. 

When,  however,  the  supply  of  heat  from  the  sun  is  interrupted 
during  long  nights,  the  radiation  which  goes  on  into  space  causes 
the  precipitation  of  a  great  part  of  the  watery  vapor  from  the  air, 
and  the  earth,  thus  deprived  of  this  protecting  shield,  becomes 
more  and  more  rapidly  cooled.  If  now  we  could  suppose  the  at- 
mosphere to  be  mingled  with  some  permanent  gas,  which  should 
possess  an  absorptive  power  like  that  of  the  vapor  of  water,  this 
cooling  process  would  be  in  a  great  measure  arrested,  and  an  effect 
would  be  produced  similar  to  that  of  a  screen  of  glass  ;  which  keeps 
up  the  temperature  beneath  it,  directly,  by  preventing  the  escape  of 
radiant  heat,  and  indirectly  by  hindering  the  condensation  of  the 
aqueous  vapor  in  the  air  confined  beneath. 

Now  we  have  only  to  bear  in  mind  that  there  are  the  best  of 
reasons  for  believing  that,  during  the  earliest  geological  periods,  all 
of  the  carbon  since  deposited  in  the  forms  of  limestone  and  of 
mineral  coal  existed  in  the  atmosphere  in  the  state  of  carbonic  acid, 
and  we  see  at  once  an  agency  which  must  have  aided  greatly  to 
maintain  the  elevated  temperature  that  then  prevailed  at  the  earth's 
surface.*  Without  doubt  the  great  extent  of  sea,  and  the  absence 

*  [The  carbonic  acid  contained  in  a  layer  of  pure  carbonate  of  lime  or  mar- 
ble, covering  the  entire  surface  of  the  globe,  and  having  a  thickness  of  8.61 
metres,  would,  if  set  free,  double  the  weight  of  the  atmosphere.  (Canadian 
Naturalist  (2),  III.  119.)  It  is  probable  that  the  amount  of  carbonic  acid 
thus  fixed  in  the  earth's  crust  must  surpass  this  many  times,  but  from  the 
activity  of  cliemical  forces  then  prevailing,  the  greater  part  of  this  was  doubt- 
less fixed  in  the  form  of  carbonate  of  lime  at  a  very  early  period  in  the  history 
of  the  globe,  so  that  the  atmosphere  in  the  palaeozoic  age  may  not  have  con- 
tained more  than  a  few  hundredths  of  carbonic  acid.  It  must  not  be  sup- 
posed that  the  whole  of  the  vast  deposits  of  limestone  which  have  since  been 
formed  are  directly  and  immediately  due  to  the  reaction  of  carbonic  acid  on 
the  alkaline  and  earthy  silicates  of  the  rocks.  A  large  part  of  the  carbonate 
of  lime  deposited  in  later  times  was  doubtless  derived  from  the  solution  of 
the  limestones  of  pre-existing  formations.  It  nevertheless  remains  true  that 
a  reaction  between  the  carbonic  acid  of  the  atmosphere  and  mineral  silicates, 
similar  to  that  of  early  times,  though  small  in  amount,  is  still  going  on  at 
the  earth's  surface.  (A  nte,  pages  10  and  20. )] 


48     THE  CHEMISTRY  OF  THE  PRIMEVAL  EARTH.     [IV. 

or  rarity  of  high  mountains,  contributed  much  towards  the  mild 
climate  of  later  ages,  when  a  vegetation  as  luxuriant  as  that  now 
found  in  the  tropics  flourished  within  the  Arctic  circle  ;  but  to 
these  causes  must  be  added  the  influence  of  a  portion  of  carbon 
which  was  afterwards  condensed  in  the  forms  of  coal  an<}  carbonate 
of  lime,  and  which  then  existed  in  the  condition  of  a  transparent 
and  permanent  gas,  mingled  with  the  atmosphere,  surrounding  the 
earth,  and  protecting  it  like  a  dome  of  glass.  To  this  effect  of  car- 
bonic acid  it  is  possible  that  other  gases  may  have  contributed. 
The  ozone,  which  is  mingled  with  the  oxygen  set  free  from  grow- 
ing plants,  and  the  marsh  gas,  which  is  now  evolved  from  decom- 
posing vegetation  under  conditions  similar  to  those  then  presented 
by  the  coal  fields,  may,  by  their  great  absorptive  power,  have  very 
well  aided  to  maintain  at  the  earth's  surface  that  high  temperature 
the  cause  of  which  has  been  one  of  the  enigmas  of  geology. 


V. 
THE  ORIGIN  OF  MOUNTAINS. 

(1861.) 

The  following  pages  are  from  a  review  entitled  Some  Points  in  American  Geology, 
which  appeared  in  the  American  Journal  of  Science  for  May,  1861,  and  was  devoted  in 
part  to  a  notice  of  the  remarkable  essay  which  forms  the  Introduction  to  the  third 
volume  of  Hall's  Paleontology  of  New  York,  from  which  numerous  extracts  are  given 
below.  Read  in  connection  with  Paper  VII.  of  the  present  volume,  on  Dynamical 
Geology,  it  will  serve  to  give  a  notion  of  the  views  of  Professor  Hall  and  the  author 
on  the  nature  and  origin  of  mountains. 

THE  sediments  of  the  carboniferous  period,  like  those  of  earlier 
formations,  exhibit,  towards  the  east,  a  great  amount  of  coarse 
sediments,  evidently  derived  from  a  wasting  continent,  and  are 
nearly  destitute  of  calcareous  beds.  In  Nova  Scotia,  Sir  Wil- 
liam Logan  found,  by  careful  measurement,  14,000  feet  of  car- 
boniferous strata;  and  Professor  Eogers  gives  their  thickness 
in  Pennsylvania  as  8,000  feet,  including  at  the  base  1,400  feet 
of  a  conglomerate,  which  disappears  before  reaching  the  Missis- 
sippi. In  Missouri,  Professor  Swallow  finds  but  640  feet  of 
carboniferous  strata,  and  in  Iowa  their  thickness  is  still  less, 
the  sediments  composing  them  being  at  the  same  time  of  finer 
materials.  f  In  fact,  as  Mr.  Hall  remarks,  throughout  the  whole 
palaeozoic  period  we  observe  a  greater  accumulation  and  a 
coarser  character  of  sediments  along  the  line  of  the  Appalachian 
chain,  with  a  gradual  thinning  westward,  and  a  deposition  of 
finer  and  farther-transported  matter  in  that  direction.  To  the 
west,  as  this  shore-derived  material  diminishes  in  volume,  the 
amount  of  calcareous  matter  rapidly  augments.  Mr.  Hall  con- 
cludes, therefore,  that  the  coal-measure  sediments  were  driven 
westward  into  an  ocean  where  there  already  existed  a  marine 
fauna.  At  length,  the  marine  limestones  predominating,  the 
3  D 


50  THE  ORIGIN   OF  MOUNTAINS.  [V. 

coal-measures  come  to  be  of  little  importance,  and  we  have  a 
great  limestone  formation  of  marine  origin,  which  in  the  Rocky 
Mountains  and  New  Mexico  occupies  the  horizon  of  the  coal, 
and,  itself  unaltered,  rests  on  crystalline  strata  like  those  of  the 
Appalachian  range.  In  truth,  Mr.  Hall  observes,  the  carbon- 
iferous limestone  is  one  of  the  most  extensive  marine  formations 
of  the  continent,  and  is  characterized  over  a  much  greater  area 
by  its  marine  fauna  than  by  its  terrestrial  vegetation. 

"  The  accumulations  of  the  coal-period  were  the  last  that 
gave  form  and  contour  to  the  eastern  side  of  our  continent,  from 
the  Gulf"  of  St.  Lawrence  to  the  Gulf  of  Mexico ;  and  as  we 
have  shown  that  the  great  sedimentary  deposits  of  successive 
periods  have  followed  essentially  the  same  course,  parallel  to 
the  mountain  ranges,  we  naturally  inquire  :  What  influence 
this  accumulation  has  had  upon  the  topography  of  our  country, 
and  whether  the  present  line  of  mountain-elevation  from  north- 
east to  southwest  is  in  any  way  connected  with  the  original 
accumulation  of  sediments."  (Hall's  Paleontology,  Vol.  III. ; 
Introduction,  p.  66.) 

The  total  thickness  of  the  palaeozoic  strata  along  the  Appala- 
chain  chain  is  about  40,000  feet,  while  the  same  formations  in 
the  Mississippi  Valley,  including  the  carboniferous  limestone, 
which  is  wanting  in  the  east,  have,  according  to  Mr.  Hall,  a 
thickness  of  scarcely  4,000  feet.  In  many  places  in  this  valley 
we  find  the  palaeozoic  formations  exposed,  exhibiting  hills  of 
1,000  feet,  made  up  of  horizontal  strata,  with  the  Potsdam 
sandstone  for  their  base,  and  capped  by  the  Niagara  limestone ; 
while  the  same  strata  in  the  Appalachians  would  give  from  ten 
to  sixteen  times  that  thickness.  Still,  as  Mr.  Hall  remarks,  we 
have  there  no  mountains  of  corresponding  altitude,  that  is  to 
say,  none  whose  height,  like  those  of  the  Mississippi  valley, 
equals  the  actual  vertical  thickness  of  the  strata.  In  the  west 
there  has  been  little  or  no  disturbance,  and  the  highest  eleva- 
tions mark  essentially  the  aggregate  thickness  of  the  strata  com- 
posing them.  In  the  disturbed  regions  of  the  east,  on  the  con- 
trary, though  we  can  prove  that  certain  formations  of  known 
thickness  are  included  in  the  mountains,  the  height  of  these  is 


V.]  THE   ORIGIN   OF  MOUNTAINS.  51 

never  equal  to  the  aggregate  amount  of  the  formations.  "  We 
tli  us  find  that  in  a  country  not  mountainous,  the  elevations 
correspond  to  the  thickness  of  the  strata,  while  in  a  mountainous 
country,  where  the  strata  are  immensely  thicker,  the  mountain 
heights  bear  no  comparative  proportion  to  the  thickness  of  the 
strata While  the  horizontal  strata  give  their  whole  ele- 
vation to  the  highest  parts  of  the  plain,  we  find  the  same  beds 
folded  and  contorted  in  the  mountain  region,  and  giving  to  the 
mountian  elevations  not  one  sixth  of  their  actual  measurement." 

Both  in  the  east  and  west  the  valleys  exhibit  the  lower 
strata  of  the  palaeozoic  series,  and  it  is  evident  that,  had  the 
eastern  region  been  elevated,  without  folding  of  the  strata,  so  as 
to  make  Jhe  base  of  the  series  correspond  nearly  with  the  sea- 
level,  as  in  the  Mississippi  Valley,  the  mountains  exposed  be- 
tween these  valleys,  and  including  the  whole  palaeozoic  series, 
would  have  a  height  of  40,000  feet ;  so  that  the  mountains 
evidently  correspond  to  depressions  of  the  surface,  which  have 
carried  down  the  bottom-rocks  below  the  level  at  which  we 
meet  them  in  the  valleys.  In  other  words,  the  synclinal  struc- 
ture of  these  mountains  depends  upon  an  actual  subsidence  of 
the  strata  along  certain  lines. 

"  We  have  been  taught  to  believe  that  mountains  are  pro- 
duced by  upheaval,  folding,  and  plication  of  the  strata,  and 
that,  from  some  unexplained  cause,  these  lines  of  elevation  ex- 
tend along  certain  directions,  gradually  dying  out  on  either  side, 
and  subsiding  at  the  extremities.  We  have,  however,  here 
shown  that  the  line  of  the  Appalachian  chain  is  the  line  of  the 
greatest  accumulation  of  sediments,  and  that  this  great  mountain- 
barrier  is  due  to  original  deposition  of  materials,  and  not  to  any 
subsequent  forces  breaking  up  or  disturbing  the  strata  of  which 
it  is  composed." 

We  have  given  Mr.  Hall's  reasonings  on  this  subject  for 
the  most  part  in  his  own  words,  and  with  some  detail,  for  we 
conceive  that  the  views  which  he  is  here  urging  are  of  the 
highest  importance  to  a  correct  understanding  of  the  theory  of 
mountains.  In  the  Canadian  Naturalist  for  December,  1859, 
p.  425,  and  in  the  American  Journal  of  Science  (2),  XXX.  137, 


52  THE  OEIGIN   OF  MOUNTAINS.  [V. 

will  be  found  an  allusion  to  the  rival  theories  of  upheaval  and 
accumulation  as  applied  to  volcanic  mountains,  the  discussion 
between  which  we  conceive  to  be  settled  in  favor  of  the  latter 
theory  by  the  reasonings  and  observations  of  Constant-Prevost, 
Scrope,  and  Lyell.  A  similar  view  to  the  former  applied  to 
mountain-chains  like  those  of  the  Alps,  Pyrenees,  and  AUe- 
ghanies,  which  are  made  up  of  aqueous  sediments,  has  been 
imposed  upon  the  world  by  the  authority  of  Humboldt,  Von 
Buch,  and  Elie  de  Beaumont,  with  scarcely  a  protest.  Buffon, 
it  is  true,  when  he  explained  the  formation  of  continents  by 
the  slow  accumulation  of  detritus  beneath  the  ocean,  conceived 
that  the  irregular  action  of  the  water  would  give  rise  to  great 
banks  or  ridges  of  sediments,  which  when  raised  above  the 
waves  must  assume  the  form  of  mountains.  Later,  in  1832,  we 
find  De  Montlosier  protesting  against  the  elevation-hypothesis 
of  Yon  Buch,  and  maintaining  that  the  great  mountain-chains 
of  Europe  are  but  the  remnants  of  continental  elevations  which 
have  been  cut  away  by  denudation,  and  that  the  foldings  and 
inversions  to  be  met  with  in  the  structure  of  mountains  are  to 
be  looked  upon  only  as  local  and  accidental. 

In  1856,  Mr.  J.  P.  Lesley  published  a  little  volume  entitled 
Coal  and  its  Topography,  in  the  second  part  of  which  he  has, 
in  a  few  brilliant  and  profound  chapters,  discussed  the  princi- 
ples of  topographical  science  with  the  pen  of  a  master.  He 
there  tells  us  that  the  mountain  lies  at  the  base  of  all  topo- 
graphical geology.  Continents  are  but  congeries  of  mountains, 
or  rather  the  latter  are  but  fragments  of  continents,  sep- 
arated by  valleys  which  represent  the  absence  or  removal  of 
mountain-land ;  and  again,  "  mountains  terminate  where  the 
rocks  thin  out." 

The  arrangement  of  the  sedimentary  strata  of  which  moun- 
tains are  composed  may  be  either  horizontal,  synclinal,  anti- 
clinal, or  vertical,  but  from  the  greater  action  of  diluvial  forces 
upon  anticlinals  in  disturbed  strata  it  results  that  great  moun- 
tain-chains are  generally  synclinal  in  their  structure,  being  in 
fact  but  fragments  of  the  upper  portion  of  the  earth's  crust 
lying  in  synclinals,  and  thus  preserved  from  the  destruction 


V.]  THE  ORIGIN   OF  MOUNTAINS.  53 

and  translation  which  have  exposed  the  lower  strata  in  the 
anticlinal  valleys,  leaving  the  intermediate  mountains  capped 
with  lower  strata.  The  effects  of  those  great  and  mysterious 
denuding  forces  which  have  so  powerfully  modified  the  surface 
of  the  globe  become  less  apparent  as  we  approach  the  equatorial 
regions,  and  accordingly  we  find  that  in  the  southern  portions 
of  the  Appalachian  chain  many  of  the  anticlinal  folds  have 
escaped  erosion,  and  appear  as  hills  of  an  anticlinal  structure. 
The  same  thing  is  occasionally  met  with  farther  north ;  thus 
Sutton  Mountain  in  eastern  Canada,  lying  between  two  anti- 
clinal valleys,  has  an  anticlinal  centre,  with  two  synclinals  on 
its  opposite  slopes.  Its  form  appears  to  result  from  three 
anticlinals,  the  middle  one  of  which  has  to  a  great  extent 
escaped  denudation. 

The  error  of  the  prevailing  ideas  upon  the  nature  of  mountain 
chains  may  be  traced  to  the  notion  that  a  disturbed  condition 
of  the  rocky  strata  is  not  only  essential  to  the  structure  of  a 
mountain,  but  an  evidence  of  its  having  been  formed  by  local 
upheaval ;  and  the  great  merit  of  De  Montlosier  and  Lesley 
(the  latter  altogether  independently)  is  to  have  seen  that  the 
upheaval  has  been  in  all  cases  not  local  but  continental,  and 
that  the  disturbance  so  often  seen  in  the  strata  is  neither  de- 
pendent upon  elevation  nor  essential  to  the  formation  of  a 
mountain. 

Such  was  the  state  of  the  question  when  Mr.  Hall  came  for- 
ward, bringing  his  great  knowledge  of  the  sedimentary  forma- 
tions of  North  America  to  bear  upon  the  theory  of  continents 
and  mountains.  These  were  first  advanced  in  his  address  de- 
livered before  the  American  Association  for  the  Advancement 
of  Science,  as  its  president,  at  Montreal,  in  August,  1857.  This 
address  was  never  published,  but  the  author's  views  were 
brought  forward  in  the  first  volume  of  his  Report  on  the 
Geology  of  Iowa,  p.  41,  and  with  more  detail  in  the  Introduc- 
tion to  the  third  volume  of  his  Paleontology  of  New  York,  from 
which  we  have  taken  the  abstract  already  given.  He  has 
shown  that  the  difference  between  the  geographical  features  of 


54  THE  ORIGIN   OF  MOUNTAINS.  [V. 

the  eastern  and  central  parts  of  North  America  is  directly  con- 
nected with  the  greater  accumulation  of  sediment  along  the 
Appalachians.  He  has  further  shown  that  so  far  from  local 
elevation  being  concerned  in  the  formation  of  these  mountains, 
the  strata  which  form  their  base  are  to  be  found  beneath  their 
foundations  at  a  much  lower  horizon  than  in  the  undisturbed 
hills  of  the  Mississippi  Valley,  and  that  to  this  depression  chiefly 
is  due  the  fact  that  the  mountains  of  the  Appalachian  range  do 
not,  like  those  hills,  exhibit  in  their  vertical  height  above  the 
sea  the  whole  accumulated  thickness  of  the  palaeozoic  strata 
which  lie  buried  beneath  their  summits 

The  lines  of  mountain-elevation  of  De  Beaumont  are,  accord- 
ing to  Hall,  simply  those  of  original  accumulations,  which  took 
place  along  current  or  shore  lines,  and  have  subsequently, 
by  continental  elevations,  produced  mountain-chains.  "  They 
were  not  then  due  to  a  later  action  upon  the  earth's  crust, 
but  the  course  of  the  chain  and  the  source  of  the  materials 
were  predetermined  by  forces  in  operation  long  anterior  to 
the  existence  of  the  mountains  or  of  the  continent  of  which 
they  form  a  part."  (p.  86.) 

It  will  be  seen  from  what  we  have  said  of  Buffon,  De  Mont- 
losier,  and  Lesley,  that  many  of  the  views  of  Mr.  Hall  are  not 
new,  but  old ;  it  was,  however,  reserved  to  him  to  complete  the 
theory  and  give  to  the  world  a  rational  system  of  orographic 
geology.  He  modestly  says :  "  I  believe  I  have  controverted 
no  established  fact  or  principle  beyond  that  of  denying  the 
influence  of  local  elevating  forces,  and  the  intrusion  of  ancient 
or  plutonic  formations  beneath  the  lines  of  mountains,  as  ordi- 
narily understood  and  advocated.  In  this  I  believe  I  am  only 
going  back  to  the  views  which  were  long  since  entertained  by 
geologists  relative  to  continental  elevations."  (p.  82.) 

The  nature  of  the  palaeozoic  sediments  of  North  America 
clearly  shows  that  they  were  accumulated  during  a  slow  pro- 
gressive subsidence  of  the  ocean's  bed,  lasting  through  the 
palaeozoic  period,  and  this  subsidence,  which  would  be  greatest 
along  the  line  of  greatest  accumulation,  was  doubtless,  as  Mr. 
Hall  considers,  connected  with  the  transfer  of  sediment  and 


V.]  THE  ORIGIN  OF  MOUNTAINS.  55 

the  variations  of  local  pressure  acting  upon  the  yielding  crust 
of  the  earth,  agreeably  to  the  view  of  Sir  John  Herschel. 
This  subsidence  of  the  ocean's  bottom  would,  according  to 
Mr.  Hall,  cause  plications  in  the  soft  and  yielding  strata. 
Lyell,  in  speculating  upon  the  results  of  a  cooling  and  con- 
tracting sea  of  molten  matter,  such  as  he  imagined  might  have 
ou,ce  underlaid  the  Appalachians,  had  already  suggested  that 
the  incumbent  flexible  strata,  collapsing  in  obedience  to  grav- 
ity, would  be  forced,  if  this  contraction  took  place  along 
narrow  and  parallel  zones  of  country,  to  fold  into  a  smaller 
space  as  they  conformed  to  the  circumference  of  a  smaller  arc, 
"  thus  enabling  the  force  of  gravity,  though  originally  exerted 
vertically,  to  bend  and  squeeze  the  rocks  as  if  they  had  been 
subjected  to  lateral  pressure."  * 

Admitting  thus  Herschel's  theory  of  subsidence  and  LyelTs 
theory  of  plication,  Mr.  Hall  proceeds  to  inquire  into  the  great 
system  of  foldings  presented  by  the  Appalachians.  The  sink- 
ing along  the  line  of  greatest  accumulation  produces  a  vast 
synclinal,  which  is  that  of  the  mountain  ranges,  and  the  result 
of  such  a  sinking  of  flexible  beds  will  be  the  production  within 
the  greater  synclinal  of  numerous  smaller  synclinal  and  anti- 
clinal axes,  which  must  gradually  decline  toward  the  margin 
of  the  great  synclinal  axis.  This  process,  the  author  observes, 
appears  to  furnish  a  satisfactory  explanation  of  the  difference 
of  slope  observed  on  the  two  sides  of  the  Appalachian  anticli- 
nals,  where  the  dips  on  one  side  are  uniformly  steeper  than 
on  the  other,  (p.  71.) 

An  important  question  here  arises,  which  is  this :  while 
admitting  with  Lyell  and  Hall  that  parallel  foldings  may  be 
the  result  of  the  subsidence  which  accompanied  the  deposition 
of  the  Appalachian  sediments,  we  inquire  whether  the  cause 
is  adequate  to  produce  the  vast  and  repeated  flexures  presented 
by  the  Alleghanies.  Mr.  Billings,  in  a  recent  paper  in  the 
Canadian  Naturalist  (Jan.,  1860),  has  endeavored  to  show 
that  the  foldings  thus  produced  must  be  insignificant  when 
compared  with  the  great  undulations  of  strata ;  whose  origin 
*  Travels  in  North  America,  First  Visit,  Vol.  I.  p.  78. 


56  THE  ORIGIN   OF  MOUNTAINS.  V. 

Professor  Kogers  has  endeavored  to  explain  by  his  theory  of 
earthquake-waves  propagated  through  the  igneous  fluid  mass 
of  the  globe,  and  rolling  up  the  flexible  crust.  We  shall  not 
stop  to  discuss  this  theory,  but  call  attention  to  another  agency 
hitherto  overlooked,  which  must  also  cause  contraction  and 
folding  of  the  strata,  and  to  which  we  have  already  elsewhere 
alluded.  (Am.  Jour.  Sci.  (2),  XXX.  138.)  It  is  the  conden- 
sation which  must  take  place  when  porous  sediments  are  con- 
verted into  crystalline  rocks  like  gneiss  and  mica-slate,  and 
still  more  when  the  elements  of  these  sediments  are  changed 
into  minerals  of  high  specific  gravity,  such  as  pyroxene,  garnet, 
epidote,  staurolite,  chiastolite,  and  chloritoid.  This  contrac- 
tion can  only  take  place  when  the  sediments  have  become 
deeply  buried  and  are  undergoing  metamorphism,  and  is,  as 
many  attendant  phenomena  indicate,  connected  with  a  softened 
and  yielding  condition  of  the  lower  strata. 

We  have  now  in  this  connection  to  consider  the  hypothesis 
which  ascribes  the  corrugation  of  portions  of  the  earth's  crust 
to  the  gradual  contraction  of  the  interior.  An  able  discussion 
of  this  view  will  be  found  in  the  American  Journal  of  Science 
(2),  III.  176,  from  the  pen  of  Mr.  J.  D.  Dana,  who,  in  common 
with  all  others  who  have  hitherto  written  on  the  subject, 
adopts  the  notion  of  the  igneous  fluidity  of  the  earth's  interior. 
We  have,  however,  elsewhere  given  our  reasons  for  accepting 
the  conclusion  of  Hopkins  and  Hennessey  that  the  earth, 
instead  of  being  a  liquid  mass  covered  with  a  thin  crust,  is 
essentially  solid  to  a  great  depth,  if  not  indeed  to  the  centre, 
so  that  the  volcanic  and  igneous  phenomena  generally  ascribed 
to  a  fluid  nucleus  have  their  seat,  as  Keferstein  and,  after  him, 
Sir  John  Herschel  long  since  suggested,  not  in  the  anhydrous 
solid  nucleus,  but  in  the  deeply  buried  layers  of  aqueous  sedi- 
ments, which,  permeated  with  water,  and  raised  to  a  high 
temperature,  become  reduced  to  a  state  of  more  or  less  com- 
plete igneo-aqueous  fusion.  So  that  beneath  the  outer  crust 
of  sediments,  and  surrounding  the  solid  nucleus,  we  may  sup- 
pose a  zone  of  plastic  sedimentary  material  adequate  to  explain 
all  the  phenomena  hitherto  ascribed  to  a  fluid  nucleus.  (Quar. 


V.]  THE  ORIGIN   OF  MOUNTAINS.  57 

Jour.  GeoL  Society,  Nov.,  1859;  Canadian  Naturalist,  Dec., 
1859 ;  Amer.  Jour.  Sci.  (2),  XXX.  136 ;  and  ante,  page  9.) 

This  hypothesis,  as  we  have  endeavored  to  show,  is  not  only 
completely  conformable  with  what  we  know  of  the  behavior 
of  aqueous  sediments  impregnated  with  water  and  exposed  to 
a  high  temperature,  but  offers  a  ready  explanation  of  all  the 
phenomena  of  volcanoes  and  igneous  rocks,  while  avoiding 
the  many  difficulties  which  beset  the  hypothesis  of  a  nucleus 
in  a  state  of  igneous  fluidity.  At  the  same  time  any  changes 
in  volume  resulting  from  the  contraction  of  the  nucleus  would 
affect  the  outer  crust  through  the  medium  of  the  more  or  less 
plastic  zone  of  sediments,  precisely  as  if  the  whole  interior 
of  the  globe  were  in  a  liquid  state. 

The  accumulation  of  a  great  thickness  of  sediment  along  a 
given  line  Would,  by  destroying  the  equilibrium  of  pressure, 
cause  the  somewhat  flexible  crust  to  subside ;  the  lower  strata 
becoming  altered  by  the  ascending  heat  of  the  nucleus  would 
crystallize  and  contract,  and  plications  would  thus  be  deter- 
mined parallel  to  the  line  of  deposition.  These  foldings,  not 
less  than  the  softening  of  the  bottom  strata,  establish  lines  of 
weakness  or  of  least  resistance  in  the  earth's  crust,  and  thus 
determine  the  contraction  which  results  from  the  cooling  of 
the  globe  to  exhibit  itself  in  those  regions  and  along  those 
lines  where  the  ocean's  bed  is  subsiding  beneath  the  accumu- 
lating sediments.  Hence  we  conceive  that  the  subsidence 
invoked  by  Mr.  Hall  (and  by  Lyell),  although  not  the  sole 
nor  even  the  principal  cause  of  the  corrugations  of  the  strata, 
is  the  one  which  determines  their  position  and  direction,  by 
making  the  effects  produced  by  the  contraction  not  only  of 
sediments,  but  of  the  earth's  nucleus  itself,  to  be  exerted  along 
the  lines  of  greatest  accumulation 

On  the  subject  of  igneous  rocks  and  volcanic  phenomena, 
Mr.  Hall  insists  upon  the  principles  which  we  were,  so  for  as 
we  know,  the  first  to  point  out,  namely,  their  connection  with 
great  accumulations  of  sediment,  and  that  of  active  volcanoes 
with  the  newer  deposits.  We  have  elsewhere  said  :  "  The 
volcanic  phenomena  of  the  day  appear,  so  far  as  we  are  aware, 


58  THE  ORIGIN  OF  MOUNTAINS.  V.] 

to  be  confined  to  regions  of  newer  secondary  and  tertiary 
deposits,  which  we  may  suppose  the  central  heat  to  be  still 
penetrating  (as  shown  by  Mr.  Babbage),  a  process  which  has 
long  since  ceased  in  the  palaeozoic  regions."  *  To  the  accu- 
mulation of  sediments  then  we  referred  both  modern  volcanoes 
and  ancient  plutonic  rocks ;  these  latter,  like  lavas,  we  regard 
in  all  cases  as  but  altered  and  displaced  sediments,  for  which 
reason  we  have  called  them  exotic  rocks.  (Am.  Jour.  Sci.  (2), 
XXX.  133.)  Mr.  Hall  reiterates  these  views,  and  calls  atten- 
tion moreover  to  the  fact  that  the  greatest  outbursts  of  igneous 
rock  in  the  various  formations  appear  to  be  in  all  cases  con- 
nected with  rapid  accumulation  over  limited  areas,  causing 
perhaps  disruptions  of  the  crust,  through  which  the  semi-fluid 
stratum  may  have  risen  to  'the  surface.  He  cites  in  this  con- 
nection the  traps  with  the  palaeozoic  sandstones  of  "Lake  Supe- 
rior, and  with  the  mesozoic  sandstones  of  Nova  Scotia  and  the 
Connecticut  and  Hudson  Valleys. 

*  Ante,  pp.  9  and  17. 


VI. 


THE  PROBABLE  SEAT  OF  VOLCANIC 
ACTION. 

(1869.) 

The  following  paper  was  published  in  the  Geological  Magazine  for  June,  1869,  and 
reprinted,  with  an  additional  paragraph,  in  the  Am.  Jour.  Science,  from  which  it  is 
here  reproduced.  It  is,  as  will  be  seen,  to  some  extent  a  reinforcement  of  the  views 
advanced  in  Papers  I.  and  II.  ;  but,  notwithstanding  the  repetitions  involved,  it  has 
been  thought  proper  to  reprint  it  entire  for  the  sake  of  the  context.  In  further  eluci- 
dation of  the  subject  I  have  appended  some  extracts  from  a  lecture  given  in  April, 
1869,  before  the  American  Geographical  Society  in  New  York,  and  published  in  its 
Proceedings,  in  which  the  distribution  of  volcanic  and  plutonic  phenomena  are  con- 
sidered. 

THE  igneous  theory  of  the  earth's  crust,  which  supposes  it  to 
have  been  at  one  time  a  fused  mass,  and  to  still  retain  in  its 
interior  a  great  degree  of  heat,  is  now  generally  admitted.  In 
order  to  explain  the  origin  of  eruptive  rocks,  the  phenomena  of 
volcanoes,  and  the  movements  of  the  earth's  crust,  all  of  which 
are  conceived  hy  geologists  to  depend  upon  the  internal  heat  of 
the  earth,  three  principal  hypotheses  have  been  put  forward. 
Of  these  the  first  supposes  that  in  the  cooling  of  the  globe  a  solid 
crust  of  no  great  thickness  was  formed,  which  rests  upon  the 
still  uncongealed  nucleus.  The  second  hypothesis,  maintained 
by  Hopkins  and  by  Poulett  Scrope,  supposes  solidification  to 
have  commenced  at  the  centre  of  the  liquid  globe,  and  to  have 
advanced  towards  the  circumference.  Before  the  last  portions 
became  solidified,  there  was  produced,  it  is  conceived,  a  condi- 
tion of  imperfect  liquidity,  preventing  the  sinking  of  the  cooled 
and  heavier  particles,  and  giving  rise  to  a  superficial  crust,  from 
which  solidification  would  proceed  downwards.  There  would 
thus  be  enclosed,  between  the  inner  and  outer  solid  parts,  a 


60     THE  PROBABLE  SEAT  OF  VOLCANIC  ACTION.     [VI. 

portion  of  uncongealed  matter,  which,  according  to  Hopkins, 
may  be  supposed  still  to  retain  its  liquid  condition,  and  to  be 
the  seat  of  volcanic  actign,  whether  existing  in  isolated  reser- 
voirs or  subterranean  lakes ;  or  whether,  as  suggested  by  Scrope, 
forming  a  continuous  sheet  surrounding  the  solid  nucleus, 
whose  existence  is  thus  conciliated  with  the  evident  facts  of  a 
flexible  crust,  and  of  liquid  ignited  matters  beneath. 

Hopkins,  in  the  discussion  of  this  question,  insisted  upon  the 
fact,  established  by  his  experiments,  that  pressure  favors  the 
solidification  of  matters  which,  like  rocks,  pass  in  melting  to  a 
less  dense  condition,  and  hence  concludes  that  the  pressure 
existing  at  great  depths  must  have  induced  solidification  of  the 
molten  mass  at  a  temperature  at  which,  under  a  less  pressure, 
it  would  have  remained  liquid.  Mr.  Scrope  has  followed  this 
up  by  the  ingenious  suggestion  that  the  great  pressure  upon 
parts  of  the  solid  igneous  mass  may  become  relaxed  from  the 
effect  of  local  movements  of  the  earth's  crust,  causing  portions 
of  the  solidified  matter  to  pass  immediately  into  the  liquid 
state,  thus  giving  rise  to  eruptive  rocks  in  regions  where  all 
before  was  solid.* 

•  Similar  views  have  been  put  forward  in  a  note  by  Eev.  0. 
Fisher,  and  in  an  essay  on  the  formation  of  mountain-chains, 
by  N.  S.  Shaler,  in  the  Proceedings  of  the  Boston  Society  of 
Natural  History,  both  of  which  appear  in  the  Geological  Maga- 
zine for  November  last.  As  summed  up  by  Mr.  Shaler,  the 
second  hypothesis  supposes  that  the  earth  "  consists  of  an 
immense  solid  nucleus,  a  hardened  outer  crust,  and  an  inter- 
mediate region  of  comparatively  slight  depth,  in  an  imperfect 
state  of  igneous  fusion."  In  this  connection  it  is  curious  to 
remark  that,  as  pointed  out  by  Mr.  J.  Clifton  Ward,  in  the 
same  Magazine  for  December  (p.  581),  Halley  was  led,  from 
the  study  of  terrestrial  magnetism,  to  a  similar  hypothesis. 
He  supposed  the  existence  of  two  magnetic  poles  situated  in  the 
earth's  outer  crust,  and  two  others  in  an  interior  mass,  sepa- 
rated from  the  solid  envelope  by  a  fluid  medium,  and  revolving, 

*  See  Scrope  On  Volcanoes,  and  his  communication  to  the  Geological  Mag- 
azine for  December,  1868. 


VI.]     THE  PROBABLE  SEAT  OF  VOLCANIC  ACTION.     61 

by  a  very  small  degree,  slower  than  the  outer  crust.*  The 
same  conclusion  was  subsequently  adopted  by  Hansteen. 

The  formation  of  a  solid  layer  at  the  surface  of  the  viscid  and 
nearly  congealed  mass  of  the  cooling  globe,  as  supposed  by  the 
advocates  of  the  second  hypothesis,  is  readily  admissible.  That 
this  process  should  commence  when  the  remaining  envelope  of 
liquid  was  yet  so  deep  that  the  refrigeration  from  that  time  to 
the  present  has  not  been  sufficient  for  its  entire  solidification, 
is,  however,  not  so  probable.  Such  a  crust  on  the  cooling 
superficial  layer  would,  from  the  contraction  consequent  on  the 
further  refrigeration  of  the  liquid  stratum  beneath,  become 
more  or  less  depressed  and  corrugated,  so  that  there  would 
probably  result,  as  I  have  elsewhere  said,  "  an  irregular  diver- 
sified surface  from  the  contraction  of  the  congealing  mass, 
which  at  last  formed  a  liquid  bath  of  no  great  depth,  surround- 
ing the  solid  nucleus."  f  Geological  phenomena  do  not,  how- 
ever, in  my  opinion,  afford  any  evidence  of  the  existence  of  yet 
unsolidified  portions  of  the  originally  liquid  material,  but  are 
more  simply  explained  by  the  third  hypothesis.  This,  like 
the  last,  supposes  the  existence  of  a  solid  nucleus  and  of  an 
outer  crust,  with  an  interposed  layer  of  partially  fluid  matter ; 
which  is  not,  however,  a  still  unsolidified  portion  of  the  once 
liquid  globe,  but  consists  of  the  outer  part  of  the  congealed 
primitive  mass,  disintegrated  and  modified  by  chemical  and 
mechanical  agencies,  impregnated  with  water,  and  in  a  state  of 
igneo-aqueous  fusion. 

The  history  of  this  view  forms  an  interesting  chapter  in 
geology.  As  remarked  by  Humboldt,  a  notion  that  volcanic 
phenomena  have  their  seat  in  the  sedimentary  formations,  and 
are  dependent  on  the  combustion  of  organic  substances,  belongs 

»  The  elevated  temperature  of  the  interior  of  the  globe  would  probably 
offer  no  obstacle  to  the  development  of  magnetism.  In  a  recent  experiment 
of  M.  Treve,  communicated  by  M.  Faye  to  the  French  Academy  of  Sciences, 
it  was  found  that  molten  cast-iron  when  poured  into  a  mould,  surrounded  by 
a  helix  which  was  traversed  by  an  electric  current,  bepame  a  strong  magnet 
when  liquid  at  a  temperature  of  1300°  C.,  and  retained  its  magnetism  while 
cooling.  (Comptes  Rendus  de  1'Acad.  des  Sciences,  February,  1869.) 

t  Ante,  page  39. 


62  THE  PROBABLE   SEAT   OF  VOLCANIC  ACTION.  [VL 

to  the  infancy  of  geplogy.  To  this  period  belong  the  theories 
of  Lemery  and  Breislak.  (Cosmos,  V.  443  ;  Otte's  translation.) 
Keferstein,  in  his  Naturgeschichte  des  Erdkorpers,  published  in 
1834,  maintained  that  all  crystalline  non-stratified  rocks,  from 
granite  to  lava,  are  products  of  the  transformation  of  sediment- 
ary strata,  in  part  very  recent,  and  that  there  is  no  well-defined 
line  to  be  drawn  between  neptunian  and  volcanic  rocks,  since 
they  pass  into  each  other.  Volcanic  phenomena,  according  to 
him,  have  their  origin  not  in  an  igneous  fluid  centre,  nor  in  an 
oxidizing  metallic  nucleus  (Davy,  Daubeny),  but  in  known 
sedimentary  formations,  where  they  are  the  result  of  a  peculiar 
kind  of  fermentation,  which  crystallizes  and  arranges  in  new 
forms  the  elements  of  the  sedimentary  strata,  with  an  evolu- 
tion of  heat  as  a  result  of  the  chemical  process.  (Naturgeschichte, 
Vol.  I.  p.  109  ;  also  Bull.  Soc.  Geol.  de  France  (1),  Vol.  VII. 
p.  197.)  In  commenting  upon  these  views  (Am.  Jour.  Science, 
July,  1860),  I  have  remarked  that,  by  ignoring  the  incandes- 
cent nucleus  as  a  source  of  heat,  Keferstein  has  excluded  the 
true  exciting  cause  of  the  chemical  changes  which  take  place  in 
the  buried  sediments.  The  notion  of  a  subterranean  combus- 
tion or  fermentation,  as  a  source  of  heat,  is  to  be  rejected  as 
irrational. 

A  view  identical  with  that  of  Keferstein,  as  to  the  seat 
of  volcanic  phenomena,  was  soon  after  put  forth  by  Sir  John 
Herschel,  in  a  letter  to  Sir  Charles  Lyell,  in  1836.  (Proc. 
Geol.  Soc.  London,  II.  548.)  Starting  from  the  suggestions 
of  Scrope  and  Babbage,  that  the  isothermal  horizons  in  the 
earth's  crust  must  rise  as  a  consequence  of  the  accumulation 
of  sediments,  he  insisted  that  deeply  bnried  strata  will  thus 
become  crystallized  by  heat,  and  may  eventually,  with  their  in- 
cluded water,  be  raised  to  the  melting  point,  by  which  process 
gases  would  be  generated,  and  earthquakes  and  volcanic  erup- 
tions follow.  At  the  same  time  the  mechanical  disturbance  of 
the  equilibrium  of  pressure,  consequent  upon  a  transfer  of  sedi- 
ments while  the  yielding  surface  reposes  on  matters  partly 
liquefied,  will  explain  the  movements  of  elevation  and  subsidence 
of  the  earth's  crust.  Herschel  was  probably  ignorant  of  the 


VI.]    THE  PROBABLE  SEAT  OF  VOLCANIC  ACTION.     63 

extent  to  which  his  views  had  been  anticipated  by  Keferstein  ; 
and  the  suggestions  of  the  one  and  the  other  seemed  to  have 
passed  unnoticed  by  geologists  until,  in  March,  1858,  I  repro- 
duced them  in  a  paper  read  before  the  Canadian  Institute 
(Toronto),  being  at  that  time  acquainted  with  Herschel's  letter, 
but  not  having  met  with  the  writings  of  Keferstein.  I  there 
considered  the  reaction  which  would  take  place  under  the  in- 
fluence of  a  high  temperature  in  sediments  permeated  with 
water,  and  containing,  besides  silicious  and  aluminous  matters, 
carbonates,  sulphates,  chlorides  and  carbonaceous  substances. 
From  these,  it  was  shown,  might  be  produced  all  the  gaseous 
emanations  of  volcanic  districts,  while  from  aqueo-igneous 
fusion  of  the  various  admixtures  might  result  the  great  variety 
of  eruptive  rocks.  To  quote  the  words  of  my  paper  just 
referred  to  :  "  We  conceive  that  the  earth's  solid  crust  of  anhy- 
drous and  primitive  igneous  rock  is  etery  where  deeply  concealed 
beneath  its  own  ruins,  which  form  a  great  mass  of  sediment- 
ary strata,  permeated  by  water.  As  heat  from  beneath  invades 
these  sediments,  it  produces  in  them  that  change  which  con- 
stitutes normal  metamorphism.  These  rocks,  at  a  sufficient 
depth,  are  necessarily  in  a  state  of  igneo-aqueous  fusion ; 
and  in  the  event  of  fracture  in  the  overlying  strata,  may  rise 
among  them,  taking  the  form  of  eruptive  rocks.  When  the 
nature  of  the  sediments  is  such  as  to  generate  great  amounts  of 
elastic  fluids  by  their  fusion,  earthquakes  and  volcanic  eruptions 
may  result,  and  these  —  other  things  being  equal  —  will  be 
most  likely  to  occur  under  the  more  recent  formations."  (Cana- 
dian Journal,  May,  1858,  Vol.'  III.  p.  207 ;  and  aide,  page  9.) 
The  same  views  are  insisted  upon  in  a  paper  On  some 
Points  in  Chemical  Geology  (Quar.  Jour.  Geol.  Soc.,  London, 
Nov.,  1859,  Vol.  XV.  p.  594),  and  have  since  been  repeatedly 
put  forward  by  me,  with  further  explanations  as  to  what  I 
have  designated  above,  the  ruin*  of  the  crust  of  anhydrous  and 
primitive  igneous  rock.  This,  it  is  conceived,  must,  by  contrac- 
tion in  cooling,  have  become  porous  and  permeable,  for  a  con- 
siderable depth,  to  the  waters  afterwards  precipitated  upon  its 
surface.  In  this  way  it  was  prepared  alike  for  mechanical  dis- 


64     THE  PROBABLE  SEAT  OF  VOLCANIC  ACTION.     VI.] 

integration,  and  for  the  chemical  action  of  the  acids,  which,  as 
shown  in  the  two  papers  just  referred  to,  must  have  been  pres- 
ent in  the  air  and  the  waters  of  the  time.  It  is,  moreover,  not 
improbable  that  a  yet  unsolidified  sheet  of  molten  matter  may 
then  have  existed  beneath  the  earth's  crust,  and  may  have  in- 
tervened in  the  volcanic  phenomena  of  that  early  period,  con- 
tributing, by  its  extravasation,  to  swell  the  vast  amount  of 
mineral  matter  then  brought  within  aqueous  and  atmospheric 
influences.  The  earth,  air,  and  water  thus  made  to  react  upon 
each  other,  constitute  the  first  matter  from  which,  by  mechan- 
ical and  chemical  transformations,  the  whole  mineral  world 
known  to  us  has  been  produced. 

It  is  the  lower  portions  of  this  great  disintegrated  and  water- 
impregnated  mass  which  form,  according  to  the  present  hypoth- 
esis, the  semi-liquid  layer  supposed  to  intervene  between  the 
outer  solid  crust  and  the  inner  solid  and  anhydrous  nucleus. 
In  order  to  obtain  a  correct  notion  of  the  condition  of  this  mass, 
both  in  earlier  and  later  times,  two  points  must  be  especially 
considered,  —  the  relation  of  temperature  to  depth,  and  that  of 
solubility  to  pressure.  It  being  conceded  that  the  increase 
of  temperature  in  descending  in  the  earth's  crust  is  due  to  the 
transmission  and  escape  of  heat  from  the  interior,  Mr.  Hopkins 
showed  mathematically  that  there  exists  a  constant  proportion 
between  the  effect  of  internal  heat  at  the  surface  and  the  rate  at 
which  the  temperature  increases  in  descending.  Thus,  at  the 
present  time,  while  the  mean  temperature  at  the  earth's  surface 
is  augmented  only  about  one  twentieth  of  a  degree  Fahrenheit, 
by  the  escape  of  heat  from  below,  the  increase  is  found  to  be 
equal  to  about  one  degree  for  each  sixty  feet  in  depth.  If, 
however,  we  go  back  to  a  period  in  the  history  of  our  globe 
when  the  heat  passing  upwards  through  its  crust  was  sufficient 
to  raise  the  superficial  temperature  twenty  times  as  much  as  at 
present,  that  is  to  say,  one  degree  of  Fahrenheit,  the  augmen- 
tation of  heat  in  descending  would  be  twenty  times  as  great 
as  now,  or  one  degree  for  each  three  feet  in  depth.  (Geol.  Jour- 
nal, VIII.  59.)  The  conclusion  is  inevitable  that  a  condition 
of  things  must  have  existed  during  long  periods  in  the  history 


VI.]    THE  PROBABLE  SEAT  OF  VOLCANIC  ACTION.     65 

of  the  cooling  globe  when  the  accumulation  of  comparatively 
thin  layers  of  sediment  would  have  been  sufficient  to  give 
rise  to  all  the  phenomena  of  metamorphism,  vulcanicity,  and 
movements  of  the  crust,  whose  origin  Herschel  has  so  well 
explained. 

Coming,  in  the  next  place,  to  consider  the  influence  of  press- 
ure upon  the  buried  materials  derived  from  the  mechanical  and 
chemical  disintegration  of  the  primitive  crust,  we  find  that,  by 
the  presence  of  heated  water  throughout  them,  they  are  placed 
under  conditions  very  unlike  those  of  the  original  cooling  mass. 
AVhile  pressure  raises  the  fusing  point  of  such  bodies  as  expand 
in  passing  into  the  liquid  state,  it  depresses  that  point  for  those 
which,  like  ice,  contract  in  becoming  liquid.  The  same  prin- 
ciple extends  to  that  liquefaction  which  constitutes  solution ; 
where,  as  is  with  few  exceptions  the  case,  the  process  is  at- 
tended with  condensation  or  diminution  of  volume,  pressure 
will,  as  shown  by  the  experiments  of  Sorby,  augment  the  solv- 
ent power  of  the  liquid.*  Under  the  influence  of  the  elevated 
temperature  and  the  great  pressure  which  prevail  at  consider- 
able depths,  sediments  should,  therefore,  by  the  effect  of  the 
water  which  they  contain,  acquire  a  certain  degree  of  liquidity; 
rendering  not  improbable  the  suggestion  of  Scheerer,  that  the 
presence  of  five  or  ten  per  cent  of  water  may  suffice,  at  temper- 
atures approaching  redness,  to  give  to  a  granitic  mass  a  liquidity 
partaking  at  once  of  the  character  of  an  igneous  and  an  aqueous 
fusion.  The  studies  by  Mr.  Sorby  of  the  cavities  in  crystals 
have  led  him  to  conclude  that  the  constituents  of  granitic  and 
trachytic  rocks  have  crystallized  in  the  presence  of  liquid  water, 
under  great  pressure,  at  temperatures  not  above  redness,  and 
consequently  very  far  below  that  required  for  simple  igneous 
fusion.  The  intervention  of  water  in  giving  liquidity  to  lavas 
has,  in  fact,  long  been  taught  by  Scrope,  and,  notwithstanding 
the  opposition  of  plutonists  like  Durocher,  Fournet,  and  Riviere, 
is  now  very  generally  admitted.  In  this  connection,  the  reader 
is  referred  to  the  Geological  Magazine  for  February,  1868,  page 
57,  where  the  history  of  this  question  is  discussed. 

*  Sorby,  Bakerian  Lecture,  Royal  Society,  1863. 


66     THE  PROBABLE  SEAT  OF  VOLCANIC  ACTION.    VI.] 

It  may  here  be  remarked,  that  if  we  regard  the  liquefaction 
of  heated  rocks  under  great  pressure,  and  in  presence  of  water, 
as  a  process  of  solution  rather  than  of  fusion,  it  would  follow 
that  diminution  of  pressure,  as  supposed  by  Mr.  Scrope,  would 
cause,  not  liquefaction,  but  the  reverse.  The  mechanical  press- 
ure of  great  accumulations  of  sediment  is  to  be  regarded  as  co- 
operating with  heat  to  augment  the  solvent  action  of  the  water, 
and  as  being  thus  one  of  the  efficient  causes  of  the  liquefaction 
of  deeply  buried  sedimentary  rocks. 

That  water  intervenes  not  only  in  the  phenomena  of  volcanic 
eruptions,  but  in  the  crystallization  of  the  minerals  of  eruptive 
rocks,  which  have  been  formed  at  temperatures  far  below  that 
of  igneous  fusion,  is  a  fact  not  easily  reconciled  with  either  the 
first  or  the  second  hypothesis  of  volcanic  action,  but  is  in  per- 
fect accordance  with  the  one  here  maintained,  which  is  also 
strongly  supported  by  the  study  of  the  chemical  composition 
of  igneous  rocks.  These  are  generally  referred  to  two  great 
divisions,  corresponding  to  what  have  been  designated  the 
trachytic  and  pyroxenic  types,  and  to  account  for  their  origin, 
a  separation  of  a  liquid  igneous  mass  beneath  the  earth's  crust 
into  two  layers  of  acid  and  basic  silicates  was  imagined  by 
Phillips,  Durocher,  and  Bunsen.  The  latter,  as  is  well  known, 
has  calculated  the  normal  composition  of  these  supposed  trachytic 
and  pyroxenic  magmas,  and  conceives  that  from  them,  either 
separately  or  by  admixture,  the  various  eruptive  rocks  are  de- 
rived; so  that  the  amounts  of  alumina,  lime,  magnesia,  and 
alkalies  sustain  a  constant  relation  to  the  silica  in  the  rock.  If, 
however,  we  examine  the  analyses  of  the  eruptive  rocks  in 
Hungary  and  Armenia,  made  by  Streng,  and  put  forward  in 
support  of  this  view,  there  will  be  found  such  discrepancies 
between  the  actual  and  the  calculated  results  as  to  throw  grave 
doubts  on  Bunsen's  hypothesis. 

Two  things  become  apparent  from  a  study  of  the  chemical 
nature  of  eruptive  rocks  :  first,  that  their  composition  presents 
such  variations  as  are  irreconcilable  with  the  simple  origin  gen- 
erally assigned  to  them  ;  and,  second,  that  it  is  similar  to  that  of 
sedimentary  rocks  whose  history  and  origin  it  is,  in  most  cases, 


VI.]  DISTRIBUTION  OF  VOLCANOES.  67 

not  difficult  to  trace.  I  have  elsewhere  pointed  out  how  the 
natural  operation  of  mechanical  and  chemical  agencies  tends  to 
produce  among  sediments  a  separation  into  two  classes,  cor- 
responding to  the  two  great  divisions  above  noticed.  From  the 
mode  of  their  accumulation,  however,  great  variations  must 
exist  in  the  composition  of  the  sediments,  corresponding  to 
many  of  the  varieties  presented  by  eruptive  rocks.  The  care- 
ful study  of  stratified  rocks  of  aqueous  origin  discloses,  in  ad- 
dition to  these,  the  existence  of  deposits  of  basic  silicates  of 
peculiar  types.  Some  of  these  are  in  great  part  magnesian, 
others  consist  of  compounds  like  anorthite  and  labradorite, 
highly  aluminous  basic  silicates  in  which  lime  and  soda  enter, 
to  the  almost  complete  exclusion  of  magnesia  and  other  bases  ; 
while  in  the  masses  of  pinite  or  agalmatolite-rock  we  have  a 
similar  aluminous  silicate,  in  which  lime  and  magnesia  are 
wanting,  and  potash  is  the  predominant  alkali.  In  such  sedi- 
ments as  these  just  enumerated  we  find  the  representatives  of 
eruptive  rocks  like  peridotite,  phonolite,  leucitophyre,  and  simi- 
lar rocks,  which  are  so  many  exceptions  in  the  basic  group  of 
Bunsen.  As,  however,  they  are  represented  in  the  sediments 
of  the  earth's  crust,  their  appearance  as  exotic  rocks,  consequent 
upon  a  softening  and  extravasation  of  the  more  easily  liquefiable 
strata  of  deeply  buried  formations,  is  readily  and  simply  ex- 
plained. 


APPENDIX. 

DISTRIBUTION   OP   VOLCANOES. 

"WE  regard  the  extravasation  of  igneous  matter,  whether  as  lava 
or  ashes  at  the  surface,  or  as  plutonic  rock  in  the  midst  of  strata,  as, 
in  its  wider  sense,  a  manifestation  of  vulcanicity  ;  and,  for  the  elu- 
cidation of  our  subject,  consider  both  those  regions  characterized  by 
great  outbursts  of  plutonic  rock  in  former  geologic  periods,  and 
those  now  the  seats  of  volcanic  activity,  which,  in  these  cases,  can 
generally  be  traced  back  some  distance  into  the  tertiary  age.  To 
begin  with  the  latter,  the  first  and  most  important  is  the  great  con- 


68  DISTRIBUTION   OF  VOLCANOES.  [VI. 

tinental  region  which  may  be  described  as  including  the  Mediterra- 
nean and  Aralo-Caspian  basins,  extending  from  the  Iberian  peninsula 
eastward  to  the  Thian-Chan  Mountains  of  central  Asia.  In  this 
great  belt,  extending  over  about  ninety  degrees  of  longitude,  are 
included  all  the  historic  volcanoes  of  the  ancient  world,  to  which 
we  must  add  the  extinct  volcanoes  of  Murcia,  Catalonia,  Auvergne, 
the  Vivarais,  the  Eifel,  Hungary,  etc.,  some  of  which  have  probably 
been  active  during  the  human  period. 

It  is  a  most  significant  fact  that  this  region  is  nearly  coextensive 
with  that  occupied  for  ages  by  the  great  civilizing  races  of  the 
world.  From  the  plateau  of  central  Asia,  throughout  their  west- 
ward migration  to  the  pillars  of  Hercules,  the  Indo-European  na- 
tions were  familiar  with  the  volcano  and  the  earthquake  ;  and  that 
the  Semitic  race  were  not  strangers  to  the  same  phenomena,  the 
whole  poetic  imagery  of  the  Hebrew  Scriptures  bears  ample  evi- 
dence. In  the  language  of  their  writers,  the  mountains  are  mol- 
ten ;  they  quake  and  fall  down  at  the  presence  of  the  Deity,  when 
the  melting  fire  burneth.  The  fury  of  his  wrath  is  poured  forth 
like  fire  ;  he  toucheth  the  hills  and  they  smoke  ;  while  fire  and  sul- 
phur come  down  to  destroy  the  doomed  cities  of  the  plain,  whose 
foundation  is  a  molten  flood.  Not  less  does  the  poetry  and  the 
mythology  of  Greece  and  of  Rome  bear  the  impress  of  that  nether 
realm  of  fire  in  which  the  volcano  and  the  earthquake  have  their 
seat.  The  influence  of  these  is  conspicuous  throughout  the  imagi- 
native literature  and  the  religious  systems  of  the  Indo-European 
nations,  whose  contact  with  terrible  manifestations  of  unseen  forces 
beyond  their  foresight  or  control  could  not  fail  to  act  strongly  on 
their  moral  and  intellectual  development  ;  which  would  have  doubt- 
less presented  very  different  phases  had  the  early  home  of  these 
races  been  in  Australia  or  on  the  eastern  side  of  the  American  conti- 
nent, where  volcanoes  are  unknown,  and  earthquakes  are  scarcely 
felt. 

Besides  the  great  region  just  indicated,  must  be  mentioned  that 
of  our  own  Pacific  slope,  from  Fuegia  to  Alaska,  whence,  along  the 
eastern  shore  of  Asia,  a  line  of  volcanic  activity  extends  to  the 
burning  mountains  of  the  Indian  archipelago.  Volcanic  islands  are 
widely  scattered  over  the  Pacific  basin,  and  volcanoes  are  conspicu- 
ous in  the  Antarctic  continent.  The  Atlantic  area  is  in  like  man- 
ner marked  by  volcanic  islands  from  Jan  Mayen  and  Iceland  to  the 
Canaries,  the  Azores,  and  the  Caribbean  Islands,  and  southward  to 
Ascension,  St.  Helena,  and  Tristan  d'Acunha. 


VI.]  DISTRIBUTION  OF  VOLCANOES.  69 

If  \ve  look  at  the  North  American  continent,  we  find  along  its 
northeastern  portion  evidences  of  great  subsidence,  and  an  accumu- 
lation of  not  less  than  40,000  feet  of  sediment  along  the  line  of  the 
Appalachians  from  the  Gulf  of  St.  Lawrence  southwards,  during  the 
palaeozoic  period.  This  region  is  precisely  that  characterized  by 
considerable  eruptions  of  plutonic  rocks  during  this  period  and  for 
some  time  after  its  close.  To  the  westward  of  the  Appalachians, 
the  deposits  of  palaeozoic  sediments  were  much  thinner,  and  in  the 
Mississippi  valley  are  probably  less  than  4,000  feet  in  thickness. 
Conformably  \vith  this,  there  are  no  traces  of  plutonic  or  volcanic 
outbursts  from  the  northeast  region  just  mentioned  throughout  this 
vast  palaeozoic  basin,  with  the  exception  of  the  shores  of  Lake  Supe- 
rior, where  we  find  the  early  portion  of  the  palaeozoic  age  marked 
.by  a  great  accumulation  of  sediments,  comparable  to  that  occurring 
at  the  same  time  in  the  region  of  New  England,  and  followed  or 
accompanied  by  similar  plutonic  phenomena.  Across  the  plains  of 
northern  Russia  and  Scandinavia,  as  in  the  Mississippi  valley,  the 
palaeozoic  period  was  represented  by  not  more  than  2,000  feet  of 
sediments,  which  still  lie  undisturbed,  while  in  the  British  Islands 
50,000  feet  of  palaeozoic  strata,  contorted  and  accompanied  by  igne- 
ous rocks,  attest  the  connection  between  great  accumulation  and 
plutonic  phenomena. 

Coming  now  to  modern  volcanoes,  we  find  them  in  their  greatest 
activity  in  oceanic  regions  where  subsidence  and  accumulation  are 
still  going  on.  Of  the  two  continental  regions  already  pointed  out, 
that  along  the  Mediterranean  basin  is  marked  by  an  accumulation 
of  mesozoic  and  tertiary  sediments,  20,000  feet  or  more  in  thick- 
ness. It  is  evident  that  the  great  mountain  zone  which  includes 
the  Pyrenees,  the  Alps,  the  Caucasus,  and  the  Himalaya  was, 
during  the  later  secondary  and  tertiary  periods,  a  basin  in  which 
vast  depositions  were  taking  place,  as  in  the  Appalachian  belt  dur- 
ing the  palaeozoic  times.  Turning  to  the  other  continental  region, 
the  American  Pacific  slope,  similar  evidences  of  great  accumulations 
during  the  same  periods  are  found  throughout  its  whole  extent, 
showing  that  the  great  Pacific  mountain-belt  of  North  and  South 
America,  with  its  attendant  volcanoes,  is,  in  the  main,  the  geological 
equivalent  or  counterpart  of  the  great  east  and  west  belt  of  the 
eastern  world.  (Proceedings  of  the  American  Geographical  Society, 
April,  1869.) 


VII. 

ON    SOME    POINTS    IN    DYNAMICAL 
GEOLOGY. 

The  following  paper,  which  appeared  in  the  American  Journal  of  Science  for  April, 
1873,  may  be  read  as  a  supplement  to  Essays  I.,  II.,  V.,  and  VI.  in  the  present  volume. 
Nearly  all  of  the  views  which  I  have  maintained  since  1858-1861  in  my  endeavors  to 
reconstruct  dynamical  geology  on  a  new  basis,  as  set  forth  in  the  essays  just  referred^ 
to,  have  of  late  been  appropriated,  without  recognition,  perhaps  unconsciously,  by 
LeConte,  Mallet,  and  others  ;  and  therefore  some  assertion  of  priority  on  my  part 
seemed  not  out  of  place.  The  reader  may  also  consult  in  this  connection  Professor  J. 
D.  Dana's  essay  on  The  Results  of  the  Earth's  Contraction  on  Cooling,  in  the  Ameri- 
can Journal  of  Science  for  June  -  September,  1873,  and  further  a  note  in  the  same 
Journal  for  November,  1873  (page  381).  containing  his  acknowledgment  of  my  claims  to 
priority  on  important  points  which  he  had  denied  me  in  the  essay  in  question. 

IN  his  late  essay  on  The  Formation  of  the  Features  of  the 
*Earth's  Crust,  in  the  American  Journal  of  Science  for  Novem- 
ber and  December,  1872,  Professor  Joseph  LeConte  has  dis- 
cussed a  wide  range  of  subjects  in  geological  dynamics,  in  a 
manner  for  which  the  student  cannot  but  be  grateful.  After 
a  consideration  of  the  arguments  with  regard  to  the  nature  of 
the  earth's  interior,  he  arrives  at  the  conclusion  that  "  the  whole 
theory  of  igneous  agencies  —  which  is  little  less  than  the  whole 
foundation  of  theoretic  geology  —  must  be  reconstructed  on  the 
basis  of  a  solid  earth  "  ;  a  conclusion  which  forms  the  starting- 
point  of  his  essay.  It  is  here  to  be  noted,  that  the  late  Wil- 
liam Hopkins,  to  whom  we  owe  one  of  our  great  arguments  in 
favor  of  a  solid  globe,  did  not  take  this  ground,  but  sought  to 
explain  the  phenomena  of  igneous  action  by  the  hypothesis  of 
portions  of  matter  still  remaining  unsolidified  at  no  great 
depth  between  the  solid  nucleus  and  the  superficial  crust. 
Dissenting  from  this  view,  though  accepting  the  general  conclu- 


VII.]         ON  SOME  POINTS  IN  DYNAMICAL  GEOLOGY.  71 

sions  of  Hopkins  and  others  as  to  a  solid  globe,  I  have  been 
endeavoring,  since  1858,  to  reconstruct,  in  the  language  of  Pro- 
fessor LeConte,  "  the  theory  of  igneous  agencies  on  the  basis  of  a, 
solid  earth"  Alone  up  to  this  time,  so  far  as  I  am  aware,  I 
have  labored  to  expand,  complete,  and  give  geological  and 
chemical  consistency  to  the  suggestion  long  since  put  forth, 
both  by  Keferstein  and  by  Sir  John  Herschel,  that  the  deeply 
buried  and  water-impregnated  strata  between  the  superficial 
crust  of  the  earth  and  the  solid  nucleus  constitute  a  region  "  of 
plastic  material  adequate  to  explain  all  the  phenomena  hitherto 
ascribed  to  a  fluid  nucleus,"  since  "  any  changes  in  volume  re- 
sulting from  the  contraction  of  the  (solid)  nucleus  would  affect 
the  outer  crust  through  the  medium  of  the  more  or  less  plastic 
zone  of  sediments  precisely  as  if  the  whole  interior  of  the  globe 
were  liquid." 

A  softening  by  heat  of  previously  solid  porous  sediments, 
filled  with  water,  was  maintained  (in  accordance  with  the  views 
of  Babbage  as  to  the  rise  of  the  isogeothermal  horizons  from 
the  deposition  of  newer  strata)  to  depend  upon  the  accumula- 
tion of  large  thicknesses  of  sediment,  the  results  of  which  heat 
and  softening  were  declared  by  me  to  offer  a  "  ready  explana- 
tion, of  all  the  phenomena  of  volcanoes  and  igneous  rocks."  This 
relation  of  volcanic  phenomena  to  great  acccumulation,  and  of 
those  of  recent  times  to  more  modern  sedimentary  deposits, 
which  was  also  maintained  by  me,  was  subsequently  insisted 
upon  and  enforced  by  Professor  James  Hall  in  the  introduction 
to  the  third  volume  of  the  Paleontology  of  New  York.  A  sum- 
ming up  of  these  views  as  put  forth  by  me  in  March,  1858,  and 
in  Xovember,  1859,  will  be  found  in  the  American  Journal  of 
Science  for  May,  1861.  (See  Essays  I.,  II.,  and  V.  of  the  present 
volume.)  In  this  last  it  was  shown,  in  opposition  to  the  no- 
tion of  Babbage  (who  had  speculated  upon  the  expansion  and 
consequent  elevation  of  the  deeply  buried  strata  by  heat),  that 
one  of  the  effects  of  heat  and  water  upon  the  buried  sediments 
would  be  condensation,  from  the  diminution  of  porosity  and 
still  more  from  the  conversion  of  the  earthy  materials  into 
crystalline  species  of  higher  specific  gravity,  thus  causing  com,- 


72  ON   SOME  POINTS  IN  DYNAMICAL  GEOLOGY.         [VII. 

traction  of  the  mass.  A  further  and  very  important  result  of 
this  accumulation  there  pointed  out  was  by  the  softening  of  the 
underlying  floor,  or  the  "  bottom  strata  to  establish  lines  of  weak- 
ness or  of  least  resistance  in  the  earths  crust,  and  thus  determine 
the  contraction  which  results  from  the  cooling  of  the  globe  to  ex- 
hibit itself  in  those  regions,  and  along  those  lines  where  the  ocean's 
bed  is  subsiding  beneath  the  accumulated  sediments."  Hence, 
I  added,  "We  conceive  the  subsidence  invoked  by  Mr.  Hall, 
though  not  the  sole  nor  even  the  principal  cause  of  the  corruga- 
tions of  the  earth's  strata,  is  the  one  which  determines  their 
position  and  direction  by  making  the  effects  produced  by  the 
contraction,  not  only  of  sediments  but  of  the  earth's  nucleus 
itself,  to  be  exerted  along  the  lines  of  greatest  accumulation." 
(Ante,  page  57.)  As  further  results  of  this  process  of  accumu- 
lation, I  also  asserted  "  the  metamorphism  of  sediments  in  situ, 
their  displacement  in  a  pasty  condition  from  igneo-aqueous  fu- 
sion as  plutoriic  rocks,  and  their  ejection  as  lavas,  with  attend- 
ant gases  and  vapors."  (Ante,  page  16.) 

With  these  conclusions,  enunciated  in  1858-1861,  we  may 
compare  those  arrived  at  by  Professor  LeCoiite  in  his  recent 
essay,  where  he  recognizes  as  consequences  of  the  heating  of 
great  thicknesses  of  sediments  accumulated  along  the  shores  of  a 
continent,  a  process  of  condensation  in  the  lower  strata,  result- 
ing in  "  contraction  and  subsidence  paripassu  with  the  deposit," 
followed  by  "  aqueo-igneous  softening  or  even  melting,  not 
only  of  the  lower  portion  of  the  sediments  themselves^  but  of 
the  underlying  strata  upon  which  they  were  deposited ;  the  sub- 
sidence probably  continues  during  this  process.  Finally,  this 
softening  determines  a  line  of  yielding  to  horizontal  pressure,  and 
a  consequent  upswelling  of  the  line  into  a  chain.  Thus  are 
accounted  for,  first,  the  subsidence,  then  the  subsequent  upheaval, 
and  also  the  metamorphism  of  the  lower  strata."  Beneath  every 
great  line  of  sediments  there  will  moreover  be  found,  according 
to  him,  a  reservoir  of  sedimentary  material  in  a  state  of  more  or 
less  complete  fusion,  in  which  volcanic  phenomena  have  their 
seat.  The  reader  cannot  fail  to  see  that  these  views  are  identi- 
cal with  those  which  I  have  so  long  advocated. 


VII.]         ON   SOME  POINTS  IN  DYNAMICAL  GEOLOGY.  73 

The  views  of  Professor  James  Hall,  as  to  the  relation  between 
great  accumulations  of  strata  and  mountain-elevations,  are  cited 
with  approval  by  LeConte,  who,  following  him,  asserts  that 
"mountain-chains  are  masses  of  immensely  thick  sediments." 
I  venture,  however,  to  remark  in  this  connection,  that  the 
views  both  of  Mr.  Hall  and  of  myself,  as  his  expounder,  have 
as  yet  been  but  imperfectly  understood  either  by  LeConte  or 
our  other  critics.  Thus  they  have  been  denned  as  "  a  theory 
of  mountains  with  the  origin  of  mountains  left  out "  ;  while  Le- 
Conte says,  "  Hall  and  Hunt  leave  the  sediments  just  after  the 
whole  preparation  has  been  made,  but  before  the  actual  moun- 
tain-formation has  taken  place."  Now,  in  fact,  so  far  as  I  am 
aware,  neither  Hall  nor  yet  myself  in  my  exposition  of  his 
views  (ante,  page  49)  has  proposed  any  theory  to  explain  this 
latter  part  of  the  process,  that  is  to  say,  the  uplifting  of  the 
deposited  sediments  which  LeConte  calls  "  the  actual  moun- 
tain-formation." Hall's  contribution  to  the  problem,  which,  as 
our  author  well  says,  forms  "  an  era  in  geological  science,"  was 
to  show  the  relation  between  mountain-chains  and  great  accu- 
mulations of  sediments  ;  to  illustrate  this  by  the  history  of  the 
palaeozoic  rocks  of  2sbrth  America ;  and  moreover  to  protest 
against  the  generally  received  theory  that  mountain  elevations 
are  due  to  local  upthrusts ;  he,  to  use  his  own  language,  "  going 
back  to  the  theories  long  since  entertained  by  geologists  rela- 
tive to  continental  elevations."  That  mountains  were  the 
remnants  of  eroded  continental  areas  had  already  been  taught 
by  Lesley,  and  long  before  by  Buffon  and  De  Montlosier.  It 
was  left  for  Hall,  through  a  new  way,  to  lead  us  back  to  these 
views ;  but  the  whole  theory  of  the  cause  of  continental  eleva- 
tions was  left  by  him  where  he  found  it.  In  my  exposition 
of  his  views,  I  have  only  endeavored,  in  addition,  to  show  in 
what  manner  a  contracting  globe  and  a  solid  nucleus  may  be 
related  to  the  great  facts  of  local  subsidence  and  accumulation. 

I  shall  not  attempt  to  follow  LeConte  in  his  objections  to 
the  views  of  Dana  and  Whitney  with  regard  to  the  uplifting 
of  mountains,  but  proceed  to  notice  briefly  his  own,  according 
to  which  the  horizontal  thrust  resulting  from  the  slow  contrac- 

4 


74  ON   SOME  POINTS  IN  DYNAMICAL  GEOLOGY.        [VII. 

tion  of.  the  nucleus  is  brought,  in  the  manner  which  I  long 
since  explained,  to  act  upon  the  great  accumulations  of  sedi- 
ment, so  that  they  are  "  crushed  together  horizontally  and 
swelled  up  vertically,"  thus  producing  not  only  plications 
and  slaty  cleavage,  but  an  amount  of  vertical  extension  "fully 
adequate  to  account  for  the  upheaval  of  the  greatest  mountain- 
chains  "  ;  the  ridges,  peaks,  gorges,  and  valleys  of  mountain- 
regions  being,  however,  the  results  of  subsequent  erosion.  This 
theory  of  the  plications  of  strata,  and  their  relations  both  to 
great  accumulations  and  to  a  contracting  nucleus,  is  fully  set 
forth  in  my  paper  of  1861,  already  quoted;  where  I  have  also 
insisted  upon  the  results  of  "the  lateral  pressure  brought  to 
bear  upon  the  strata  in  an  elongated  basin  (of  subsidence)  by 
the  contraction  of  the  globe." 

But  while  admitting  that  the  process  here  described  must 
cause  elevations  of  the  compressed  strata,  it  must  be  said  that 
it  fails  to  solve  the  problem  of  the  uplifting  of  mountain- 
regions,  the  strata  of  which  have,  in  many  cases,  undergone 
neither  folding  nor  lateral  compression,  but  are  nearly  or  quite 
horizontal.  Foldings,  contortions,  and  slaty  cleavage,  though 
met  with  in  many  mountain-regions,  are,  in  fact,  accidents 
which  are  to  be  left  out  of  view  in  considering  the  origin  of 
mountains.  The  student  of  physical  geography  may  learn 
from  the  great  elevated  plateaus  of  the  globe  the  truth  of  De 
Montlosier's  statement,  that  the  great  mountain-chains  of 
Europe  are  but  the  remains  of  continental  elevations  which 
have  been  cut  away  by  denudation,  and  that  the  foldings  and 
inversions  to  be  met  with  in  the  structure  of  mountains  are  to 
be  looked  upon  only  as  local  and  accidental.  (Ante,  page  52.) 
In  a  similar  spirit  Jukes  remarks  that  we  learn  "  how  complete- 
ly the  present  surface  of  the  earth  is  a  sculptured  surface  carved 
out  by  denudation,  and  how  little,  as  a  rule,  it  is  effected  by 
the  dislocations,  upheavals  and  convolutions  of  the  rocks  be- 
neath it."  (Manual  of  Geology,  3d  ed.,  449.)  In  the  case  of 
the  uplifted  paleozoic  basin  of  eastern  North  America,  as  Hall 
has  well  shown,  the  process  of  elevation  was  the  same  for 
the  thicker  and  corrugated  sediments  of  the  eastern  portion 


VII.]          ON  SOME  POINTS  IN  DYNAMICAL  GEOLOGY.  75 

and  for  the  thinner  and  undisturbed  strata  of  the  valley  of 
the  upper  Mississippi.  The  hills  in  the  latter  region,  built 
up  of  1,000  feet  of  horizontal  beds,  having  the  Potsdam 
sandstone  at  the  base,  and  capped  by  the  Niagara  limestone, 
show  us  the  production  of  mountains  by  erosion,  uncompli- 
cated by  the  accidents  which  make  their  study  more  difficult 
in  regions  where  contortion  of  the  strata  has  supervened.  Hall 
has  also  noted  in  this  connection  the  nearly  horizontal  strata 
of  the  Catskill  Mountains. 

The  question  of  the  structure  and  the  origin  of  the  Appa- 
lachians has  been  complicated  by  the  assumption  that  the 
crystalline  strata  which  constitute  their  higher  portions  are 
altered  sediments  of  palaeozoic  age,  rather  than  parts  of  an  an- 
cient continent  of  eozoic  rocks  which  formed  the  eastern  bor- 
der of  the  palaeozoic  sea,  corresponding  to  the  Rocky  Moun- 
tains on  the  west.  The  former  view  has  been  very  generally 
held  by  American  geologists,  and  was  maintained  by  the  pres- 
ent writer  until  1870,  when  he  endeavored  to  show  that  the 
crystalline  rocks  of  New  England,  and  their  lithological  repre- 
sentatives both  to  the  southwest  and  the  northwest,  are  of 
pre-palaeozoic  age,  and  in  part  Laurentian.  (Amer.  Jour.  Sci- 
ence (2),  L.  83;  also  Address  before  the  American  Association, 
Indianapolis,  1871,  Paper  XIII.  of  this  volume.)  This  view, 
already  before  maintained  by  Credner  and  by  Euimons,  is  now 
advocated  by  LeConte,  who  conceives  that  the  gneissic  region 
of  the  Atlantic  slope  is  Laurentian,  and  was  probably  "  land 
during  the  palaeozoic  times,"  constituting  an  "eastern  conti- 
nental mass,"  which,  judging  from  the  immense  thickness  of 
sediments  in  the  eastern  parts  of  the  palaeozoic  area,  must  have 
been  of  great  extent.  A  similar  view  was  put  forward  by 
H.  D.  Rogers  in  1842,  and  again  by  James  Hall  in  1859, 
when,  after  describing  these  palaeozoic  sediments,  he  said,  "  We 
may  have  had  a  coast-line  nearly  parallel  to  and  coextensive 
with  the  Appalachians  "  (Paleontology,  Vol.  III.  p.  96,  note) ; 
commenting  upon  which,  in  1861,  I  asserted  that  these  coarse 
sediments  "  were  evidently  derived  from  a  wasting  continent." 
In  a  paper  read  before  the  American  Geographical  Society, 


76  ON   SOME  POINTS  IN  DYNAMICAL  GEOLOGY.         [VII. 

"New  York,  November  12,  1872,  I  adduced  a  further  argument 
in  favor  of  such  a  pre-palseozoic  continent  to  the  eastward, 
from  the  climatic  conditions  of  great  dryness  which  gave  rise 
in  the  palseozoic  region  of  North  America  to  deposits  of  salt, 
gypsum,  and  dolomite  over  considerable  areas  from  Nova 
Scotia  to  Michigan  and  Ohio,  and  from  the  time  of  the  Cal- 
ciferous  formation  to  the  Lower  Carboniferous.  (Engineering 
and  Mining  Journal,  January  14  and  23,  1873.) 

In  concluding  his  essay,  Professor  LeConte  declares  that  an 
important  problem  in  geological  dynamics  remains,  in  his  opin- 
ion, unsolved,  namely,  the  cause  of  those  "great  and  wide-spread 
oscillations  which  have  marked  the  great  divisions  of  time,  and 
have  left  their  impress  in  the  general  unconformability  of  the 
strata  "  ;  the  last  being  that  of  the  post-pliocene  period.  Now, 
it  is  precisely  the  upward  movements  of  this  kind  which  con- 
stitute the  continental  elevations  of  De  Montlosier,  Hall,  and 
myself,  giving  rise  to  plateaus,  and  by  the  partial  erosion  and 
denudation  of  these  to  mountains.  The  cause  of  these  conti- 
nental elevations  was  not  discussed  by  Hall,  and  is  by  LeConte 
declared  to  be  unexplained ;  while  such  is  the  case,  "  the  ac- 
tual mountain-formation,"  to  use  his  words,  is  still  unaccounted 
for.  That  these  gentle  and  widespread  movements  of  oscilla- 
tion are,  however,  in  some  way  not  yet  clearly  explained,  con- 
nected with  the  contracting  of  the  nucleus  and  the  consequent 
conforming  thereto  of  the  envelope,  we  can  scarcely  doubt ;  or 
that  the  latter,  from  its  nature  and  origin,  must  present  great 
differences  in  constitution  and  in  flexibility  in  its  various  parts. 
From  this  it  might  be  expected  that  the  movements  imparted 
to  the  envelope  alike  by  the  process  of  secular  cooling  and  con- 
traction of  the  nucleus,  and  by  the  disturbance  of  the  equilib- 
rium of  pressure  consequent  on  the  processes  of  erosion  and 
sedimentation,  would  give  rise  to  seemingly  irregular  oscilla- 
tions, resulting  in  the  depression  or  the  elevation  of  consider- 
able areas,  constituting  continental  movements. 

The  grave  question  here  arises  as  to  whether  the  heat  which 
plays  such  an  important  part  in  the  phenomena  under  con- 
sideration is  a  cause  or  an  effect  of  the  activities  beneath  the 


VIL]         ON  SOME  POINTS  IN  DYNAMICAL  GEOLOGY.  77 

earth's  surface.  Starting  from  the  notion  of  an  igneous  centre, 
Babbage  and  Herschel  adopted  the  first  view,  in  which  I  have 
followed  them,  maintaining  that  the  heat  from  a  yet  uncooled 
nucleus  is  the  efficient  cause  of  all  igneous  and  volcanic  mani- 
festations. According  to  Keferstein,  on  the  other  hand,  the 
hypothesis  of  an  incandescent  nucleus  is  unnecessary,  and  the 
internal  heat  results  from  what  he  called  a  fermentation  among 
the  deeply  buried  sedimentary  layers.  A  view  which  unites 
these  two  is  proposed  by  LeConte,  who  suggests  that  heat 
from  a  central  source  invading  the  buried  sediments  may  there 
excite  chemical  action,  which  will,  in  its  turn,  evolve  heat, 
and  thus  greatly  augment  their  temperature.  It  is,  however, 
I  think,  probable  that  any  chemical  processes  which  may  be 
set  up  in  the  buried  sediments  for  their  conversion  into  igne- 
ous rocks  and  volcanic  products  would  absorb  rather  than  gen- 
erate heat. 

In  his  remarkable  study  of  the  Secular  Cooling  of  the 
Earth  (Trans.  Royal  Soc.  Edinb.,  XXIII.  pt.  1,  p.  157),  Sir 
William  Thomson  arrives  at  the  conclusion  that  the  observed 
mean  rate  of  increase  in  descending  in  the  earth's  crust  will 
continue  with  but  little  variation  for  100,000  feet,  but  will 
gradually  diminish  at  greater  depths,  from  an  increase  of  con- 
ducting power.  Estimating  with  him  the  rate  of  increase  at 
one  degree  of  Fahrenheit  for  fifty-one  feet,  it  would  require 
the  depth  just  named,  or  about  nineteen  miles,  to  give  a  tem- 
perature of  2,000°  F.,  which  may  be  supposed  sufficient  to  pro- 
duce the  chemical  actions  required.  But  it  is  probable  that 
the  seat  of  volcanic  activity  may  be  much  less  profound  than 
above  supposed,  in  which  case  the  central  heat  would  be  in- 
adequate. Chemical  action,  as  suggested  by  Keferstein  and 
LeConte,  being  rejected  as  a  source  of  heat,  there  however 
remained  the  hypothesis  that  thermal  effects  might  result  from 
local  physical  causes,  and  that  the  immense  mechanical  force 
which  is  exerted  in  the  movements  of  the  earth's  crust  might  be 
converted  into  heat.  This  view  was,  so  far  as  I  am  aware,  first 
suggested  by  George  L.  Yose,  whose  review  of  Orographic  Geol- 
ogy, a  very  valuable  contribution  to  the  literature  of  the  sub- 


78  ON   SOME  POINTS  IN  DYNAMICAL  GEOLOGY.        [VII. 

ject,  was  published  in  1866.  In  it,  while  recognizing  with 
Sorby  the  conversion  of  mechanical  force  into  chemical  action, 
he  insists  that  "  the  enormous  pressure  generated  in  the  fold- 
ing of  masses  of  rocks  the  depth  of  which  is  measured  by- 
miles  "  is  an  agent  potent  to  produce  changes  both  mechanical 
and  chemical.  XThe  causes  of  the  conversion  of  sediments  into 
plutonic  rocks  like  granite,  he  conceives  to  be  "mechanical 
compression,  with  the  heat  and  chemical  action  which  proceed 
therefrom,"  and  adds  in  a  note,  alluding  to  the  view  which 
explains  their  conversion  by  the  action  of  heat  from  beneath, 
"  we  should  prefer  to  get  the  heat  needed  by  the  compression 
which  accompanies  the  disturbance  of  the  strata  where  meta- 
morphism  occurs."  (Orographic  Geology,  pp.  129,  130.)*  This 
suggestion  of  Vose  is  sustained  by  the  late  researches  of  Robert 
Mallet,  who  concludes  that,  "  as  the  solid  crust  sinks  together 
to  follow  down  the  shrinking  nucleus,  the  work  expended  in 
mutual  crushing  and  dislocation  of  its  parts  is  transformed  into 
heat,  by  which,  at  the  places  where  the  crushing  sufficiently 
takes  place,  the  material  of  the  rock  so  crushed  and  that  adja- 
cent to  it  are  heated  even  to  fusion.  The  access  of  water  at 
such  points  determines  volcanic  eruption."  (American  Journal 
of  Science,  III.  iv,  411.)  To  this  it  may  be  added,  that, 
inasmuch  as  the  crushing  process  takes  place  in  strata  which, 
from  their  depth,  are  already  at  an  elevated  temperature,  the 
heat  developed  by  the  mechanical  process  comes  in  to  supple- 
ment that  derived  by  conduction  from  the  igneous  centre. 

*  It  was  not  until  after  the  publication  of  this  paper  that  I  became  aware 
that  Professor  Henry  Wurtz  had  previously  enunciated  the  view  suggested  by 
Vose  and  adopted  and  applied  by  Mallet.  In  a  paper  read  before  the  Amer- 
ican Association  for  the  Advancement  of  Science,  at  Buffalo,  in  August,  1866, 
and  published  in  the  American  Journal  of  Mining  for  January  25,  1868,  under 
the  title  of  Gold-Genetic  Metamorphism,  etc.,  Professor  Wurtz  concludes  that 
"  the  tremendous  dynamic  agencies  whose  effects  of  upheaval,  subsidence,  dis- 
ruption and  displacement  we  find  so  widely  manifest,  while  doubtless  them- 
selves engendered  of  the  pent-up  heat-energy  of  the  interior,  must  have  given 
birth  to  or  been  in  part  transmuted  into  heat-motion,"  and  proceeds  to  say  that 
in  the  heat  which  must  be  evolved  in  these  movements  we  may  find  an  explana- 
tion of  metamorphic  changes,  and  of  "  thermal  springs  and  many  like  phe- 


VII. ]         ON  SOME  POINTS  IN  DYNAMICAL  GEOLOGY.  79 

Moreover,  these  strata  already  include,  not  only  water,  but 
the  compounds  of  chlorine,  sulphur,  and  carbon  necessary  for 
the  generation  of  the  various  gases  which  are  the  frequent  ac- 
companiments of  volcanic  eruptions.*  With  the  contributions 
of  Vose  and  Mallet,  the  theory  of  volcanic  action  advocated  by 
Keferstein,  Herschel  and  myself  would  seem  to  be  wellnigh 
complete. 

*  That  the  view  so  fully  set  forth  in  papers  I.  and  II.  of  the  present  vol- 
ume, in  the  years  1858  and  1859,  as  to  the  origin  of  volcanic  products,  is  the 
one  now  adopted  by  Mallet,  appears  from  the  following  extract  of  a  letter 
by  him  in  Nature,  for  March  20,  1873  :  "  There  is  just  that  general  similarity 
in  the  constitution  of  volcanic  products  which  we  should  expect  to  result 
from  the  heating  or  the  fusion  together  of  the  beds,  more  or  less  silicious, 
aluminous,  magnesian,  or  calcareous,  mixed  with  metallic  oxides  or  other 
compounds,  and  often  with  carbon,  boron,  and  other  elements,  all  variously 
superposed  or  mixed,  which  constitute  the  known  crust  of  the  earth." 


VIII. 

ON  LIMESTONES,  DOLOMITES  AND 

GYPSUMS. 

(1858-1866.) 

The  results  of  the  author's  researches  on  the  chemistry  of  the  salts  of  lime  and 
magnesia,  undertaken  with  reference  to  the  theory  of  mineral-waters  and  the  origin  of 
calcareous  and  magnesian  rocks,  were  first  announced  in  the  American  Journal  of  Sci- 
ence for  July,  1858,  and  subsequently  more  at  length  in  an  essay  in  that  journal  for 
September  and  November,  1859.  This  paper,  which  extended  over  thirty-six  pages, 
was  divided  into  five  parts,  of  which  the  first  treats  of  the  action  of  solutions  of  bicar- 
bonate of  soda  on  the  soluble  salts  of  lime  and  magnesia  ;  the  second  on  the  reactions 
between  solutions  of  bicarbonate  of  lime  and  the  sulphates  of  soda  and  magnesia ; 
the  third  describes  the  production  of  the  double  carbonate  of  lime  and  magnesia 
(dolomite) ;  the  fourth  discusses  various  facts  in  the  history  of  gypsums,  dolomites, 
magnesites,  and  limestones  ;  and  the  fifth  treats  of  the  mode  of  formation  of  these 
rocks.  The  continuation  of  the  subject  in  the  same  journal  for  July,  1866,  occupies 
nineteen  pages,  and  includes  researches  on  the  hydrated  double  carbonates  of  lime 
and  magnesia,  on  supersaturated  solutions  of  these  two  carbonates,  and  on  the  alleged 
decomposition  of  gypsum  by  dolomite,  besides  further  experiments  on  the  artificial 
production  of  dolomite. 

Allusions  to  some  of  the  results  obtained  are  made  in  paper  IV.,  and  many  more 
of  the  results  are  embodied  in  the  one  on  Natural  Waters  (IX.),  while  in  XIII.  will  be 
found  a  brief  summary  of  the  results  so  far  as  the  origin  of  dolomites  and  magnesian 
limestones  is  concerned.  I  have  thought  it  well  to  reproduce  in  the  present  collection 
some  few  selections  from  the  fifth  part  of  the  essay  of  1859,  and  to  preface  them  by  a 
translation  of  parts  of  a  letter  written  to  Elie  de  Beaumont  and  printed  in  the  Comptes 
Rendus  of  the  French  Academy  of  Science  for  June  9,  1862,  and  subsequently  in  the 
Canadian  Naturalist. 

FROM  THE  COMPTES  RENDUS  OF  THE  FRENCH  ACADEMY 
OF  SCIENCES,  JUNE  9,  1862. 

ON  the  28th  of  October,  1844,  a  memoir  was  deposited  with 
the  Academy  by  the  illustrious  Cordier.  Being  in  a  sealed 
packet,  its  contents  remained  unknown  until  after  his  death, 
when,  at  the  request  of  his  widow,  the  seal  was  broken,  and 
the  paper,  which  bears  the  date  of  October  22,  1844,  was  first 
made  public  in  the  Comptes  Rendus  of  the  Academy  for  Febru- 


VIII.]      CHEMISTRY  OF  LIMESTONES  AND  DOLOMITES.  81 

ary  17,  1862.  In  this  remarkable  memoir,  which  has  for  its 
title,  On  the  Origin  of  the  Calcareous  Rocks  which  do  not  be- 
long to  the  Primordial  Crust  (De  Vorigine  des  roches  calcaires, 
etc.),  the  author  gives  his  views  upon  the  formation  of  limestone 
and  dolomite.  He  rejects  Von  Buch's  theory  of  dolomitiza- 
tion,  which  still  finds  some  supporters,  and  which  supposes 
that  the  magnesia  was  introduced  subsequent  to  the  deposition 
of  the  sediments,  by  a  "  certain  mysterious  action  of  intrusive 
pyroxenic  rocks  "  which  have  been  ejected  in  the  vicinity  of 
deposits  of  pure  limestone.  Mr.  Cordier  also  combats  the  idea 
that  these  last  have  been  formed  entirely  of  the  debris  of  testa- 
cea  and  zoophytes,  which,  according  to  him,  form  but  a  small 
proportion  of  limestone-formations.  Going  back  still  further, 
he  finds  the  source  alike  of  the  carbonate  of  lime  of  these 
organic  remains,  and  of  the  great  mass  of  calcareous  rocks,  in 
certain  chemical  reactions.  The  pure  limestones,  according  to 
him,  pass  into  magnesian  limestones  by  an  admixture  of  dolo- 
mite, and  form  thus  a  transition  to  the  pure  dolomites,  so  that 
we  must  admit  a  common  origin  for  all  these  rocks.  The  source 
of  the  two  carbonates  which  compose  them,  according  to  Mr. 
Cordier,  is  to  be  found  in  the  reaction  of  carbonate  of  soda  upon 
the  chlorides  of  calcium  and  magnesium  in  sea- water ;  the  car- 
bonate of  soda  being  derived  from  the  decomposition  of  feld- 
spars, from  alkaline  springs,  and  from  plutonic  emanations. 
This  alkaline  salt,  reacting  upon  the  salts  of  sea-water,  would 
give  rise  to  chloride  of  sodium  and  carbonate  of  lime,  and,  under 
certain  conditions,  to  calcareo-magnesian  precipitates.  From 
this  reaction  must  result  a  secular  variation  in  the  composition 
of  the  ocean,  which  corresponds  to  the  progressive  changes  in 
the  marine  fauna  of  successive  geological  epochs. 

Such  is  the  theory  of  Mr.  Cordier,  which  is  now  published, 
for  the  first  time,  in  1862  ;  and  which  I  have  thus  noticed  in 
order  to  call  the  attention  of  the  Academy  to  my  own  published 
papers,  in  which  I  have  maintained  similar  views  for  the  last 
four  years.  [See,  for  the  origin  of  carbonate  of  lime,  the  first 
paper  in  the  present  volume,  an  abstract  of  which  was  given 
in  the  letter  of  which  this  is  a  part.] 

4»  F 


82  CHEMISTRY  OF  LIMESTONES  AND  DOLOMITES.      [VIII. 

In  the  American  Journal  of  Science  for  1859  will  be  found 
the  results  of  a  series  of  investigations  of  the  reactions  of 
solutions  of  bicarbonate  of  soda  with  sea-water,  and  upon  the 
conditions  required  for  the  precipitation  of  carbonate  of  mag- 
nesia and  the  formation  of  dolomite.  I  have  there  also  shown 
the  mutual  decomposition,  at  ordinary  temperatures,  of  solutions 
of  bicarbonate  of  lime  and  sulphate  of  magnesia,  resulting  in 
the  formation  of  gypsum  and  of  a  soluble  bicarbonate  of  mag- 
nesia, which  becomes  the  source  of  dolomite  or  of  magnesite. 
A  notice  of  the  first  part  of  these  researches  will  be  found  in 
the  Comptes  Rendus  for  May  23,  1859.  In  the  continuation 
of  them,  as  cited  above,  it  is  shown  that  the  association  of  mag- 
nesian  and  pure  limestones  establishes  the  fact  that  these  rocks 
have  both  been  deposited  as  sediments,  and  that  the  hypothesis 
which  explains  the  origin  of  dolomites  by  a  subsequent  altera- 
tion of  pure  limestones  is  inadmissible.  It  is  also  shown  that 
great  portions  of  limestone,  even  in  fossiliferous  formations, 
have  the  characters  of  precipitates  resulting  from  chemical  re- 
actions, and  have  never  formed  part  of  organized  beings ;  which 
last,  moreover,  owe  their  carbonate  of  lime  to  similar  reactions. 

My  views  upon  the  composition  of  the  primitive  ocean  were 
further  supported  by  the  analyses  of  numerous  saline  waters 
from  lower  palaeozoic  limestones.  In  these  waters,  the  bases  of 
which  are  almost  wholly  in  the  condition  of  chlorides,  about 
one  half  of  the  chlorine  is  combined  with  sodium,  and  the 
other  half  is  nearly  equally  divided  between  calcium  and  mag- 
nesium. 

The  Academy  will  perceive,  from  the  short  analysis  above 
given,  the  extent  and  the  importance  of  my  generalizations,  with 
which  the  ideas  of  Mr.  Cordier  are,  for  the  most  part,  in  per- 
fect accordance.  It  will  further  be  observed,  that  the  publica- 
tion of  Mr.  Leymerie,  in  which  similar  views  are,  to  a  cer- 
tain extent,  indicated  (see  the  Comptes  Eendus  of  March  10, 
1862),  dates  only  from  1861,  while  my  own  papers  appeared 
in  1858  and  1859. 

My  researches  upon  the  origin  of  dolomites  and  limestones 
fully  justify  the  previsions  of  Mr.  Cordier.  He,  however,  in 


VIII.]         CHEMISTRY  OF  DOLOMITES  AND   GYPSUMS.  83 

his  theory,  excepted  the  limestones  of  primitive  formations, 
but  these  are  regarded  by  modern  geologists  as  also  sediment- 
ary formations,  and  consequently  offer  no  exception  to  the 
general  view.  The  different  sources  of  carbonate  of  soda  indi- 
cated by  Mr.  Cordier  may  moreover  be  reduced  to  a  single 
one,  inasmuch  as  both  the  salts  of  alkaline  springs,  and  those 
of  what  he  calls  plutonic  emanations,  are  probably  derived 
from  the  decomposing  feldspathic  minerals  of  sedimentary 
rocks.  The  argillaceous  rocks,  deprived  of  a  large  proportion 
of  the  alkali  which  they  once  contained  in  the  form  of  feld- 
spars, are  the  equivalents  of  the  limestones  which  have  been 
formed  at  the  expense  of  the  chloride  of  calcium  of  the  primi- 
tive ocean. 


EXTRACTS  FROM  A  PAPER  IN  THE  AMERICAN  JOURNAL  OF 
SCIENCE  FOR  NOVEMBER,  1859,  ON  THE  SALTS  OF  LIME 
AND  MAGNESIA  AND  THE  FORMATION  OF  GYPSUMS  AND 
MAGNESIAN  ROCKS. 

The  theory  of  the  formation  of  magnesian  sediments  will  be 
readily  understood  from  the  experiments  which  have  been  de- 
scribed in  the  earlier  parts  of  this  paper ;  but  before  proceeding 
to  its  consideration  I  wish  to  call  attention  to  the  results  of 
the  concentration  by  evaporation  of  natural  waters  in  basins 
without  an  outlet.  If  such  a  basin  contain  sea-water,  the 
gypsum,  being  insoluble  in  a  saturated  brine,  will  be  entirely 
deposited  before  the  crystallization  of  the  sea-salt,  and  there 
will  remain  a  liquid  containing  no  lime-salts,  but  chlorides  of 
sodium  and  magnesium,  with  a  large  amount  of  sulphate  of 
magnesia.  Such  are  the  waters  of  Lake  Elton  and  many  of  the 
brine-pools  of  the  Eussian  steppes  ;  while  on  the  contrary  the 
saturated  brines  of  the  Dead  Sea  and  some  other  salt  lakes 
contain  little  sulphate,  but  abundance  of  chloride  of  calcium, 
and  if  they  are  the  residues  of  sea- water,  have  been  modified 
by  additions  of  this  salt,  which  has  converted  the  sulphate  of 
magnesia  into  chloride  of  magnesium  and  gypsum,  the  calca- 
reous chloride  remaining  in  excess. 


84  CHEMISTRY  OF  DOLOMITES  AND  GYPSUMS.         [VIII. 

But  while  some  of  these  saline  lakes  may  be  supposed  to 
be  basins  of  sea-water,  modified  by  evaporation  either  alone 
or  conjoined  with  the  influx  of  foreign  saline  matters,  others 
were  evidently  once  fresh-water  lakes  in  which,  the  loss  of 
water  by  evaporation  being  equal  to  the  supply,  have  grad- 
ually accumulated  the  soluble  salts  of  all  the  rivers  and  springs 
flowing  into  the  lake.  We  may  arrive  at  some  notion  of  the 
diverse  natures  of  the  different  saline  lakes  which  would  be 
formed  in  this  way  if  we  suppose  the  waters  of  different 
European  rivers  to  be  subjected  to  evaporation  under  con- 
ditions like  those  of  the  salt  lakes  of  western  Asia.  In  the 
waters  of  the  Elbe  and  Thames  chlorides  greatly  predominate 
(in  the  latter  with  gypsum),  with  small  amounts  of  magnesian 
salts,  and  the  evaporation  of  these  waters  would  give  rise  to 
lakes  containing  a  large  proportion  of  common  salt.  In  the 
Seine,  on  the  contrary,  sulphate  of  lime  predominates,  while 
the  waters  of  the  Rhine,  the  Danube,  the  Arr,  and  the  Arve 
contain  but  small  amounts  of  chlorides  and  large  proportions 
of  sulphates  of  lime  and  magnesia. 

In  other  rivers  we  find  alkaline  salts.  The  Loire  at  Orleans, 
according  to  Deville,  contains  in  100,000  parts,  13.46  of  solid 
matters,  of  which  35.0  p.  c.  is  carbonate  of  lime  and  30.0  p.  c. 
silica ;  while  two  thirds  of  the  more  soluble  salts  consist  of 
carbonate  of  soda.  In  the  waters  of  the  Garonne,  with  as 
large  a  proportion  of  silica  and  more  carbonate  of  lime,  the 
carbonate  of  soda  equals  one  fourth  of  the  soluble  salts ;  while 
100,000  parts  of  the  water  of  the  Ottawa,  according  to  my 
analysis,  contain  6.11  parts  of  solid  matters,  consisting  of  car- 
bonate of  lime  2.48,  carbonate  of  magnesia  0.69,  silica  2.06, 
sulphates  and  chlorides  of  potassium  and  sodium  0.47,  and 
carbonate  of  soda  0.41.  Silica,  although  more  abundant  in 
alkaline  river-waters,  is  not  wanting  in  waters  containing 
neutral  earthy  salts  like  the  Seine  and  the  Ehone,  of  the  solid 
matters  of  which,  according  to  Deville,  it  forms  respectively 
10.0  and  13.0  p.  c.  (Annales  de  Chimie  et  de  Physique  (3), 
XXIII.  32.)  The  waters  which  rise  from  the  lower  palaeozoic 
shales  of  the  St.  Lawrence  valley  are,  as  I  have  shown,  re- 


VIII.]         CHEMISTRY  OF  DOLOMITES  AND  GYPSUMS.  85 

markable  for  the  predominance  of  alkaline  salts,  which  some- 
times amount  to  one  thousandth,  or  to  more  than  one  half  the 
solid  matters  present.  These  waters  are  distinguished  from 
the  river- waters  just  mentioned  by  their  comparatively  small 
amounts  of  silica  and  earthy  carbonates,  and  by  the  presence 
of  a  notable  proportion  of  borates.* 

"We  may  here  refer  to  the  strongly  alkaline  waters  furnished 
by  the  artesian  wells  of  Paris  and  London  as  evidences  of  the 
abundance  of  alkaline  carbonates  in  natural  waters,  and  to  the 
springs  of  Vichy  and  Carlsbad,  the  latter  of  which,  according 
to  the  calculations  of  Gilbert,  furnish  annually  more  than  thir- 
teen millions  of  pounds  of  carbonate  of  soda.  The  evaporation 
of  these  alkaline  waters,  whether  of  rivers  or  of  springs,  must 
give  rise  to  natron-lakes  like  Lake  Van  and  those  of  the  plains 
of  Araxes,  Lower  Egypt,  and  Hungary.  (Bischof,  Lehrbuch, 
II.  1143.) 

The  carbonate  of  soda  contained  in  these  waters  has  its 
source  in  the  decomposition  of  feldspathic  minerals,  and  shows 
the  continuance  in  our  time  of  a  process  whose  great  activity 
in  former  geologic  ages  is  attested,  as  I  have  elsewhere  main- 
tained, by  vast  accumulations  of  argillaceous  sediments  de- 
prived of  a  large  portion  of  their  alkali,  and  also  by  the  car- 
bonate of  lime  which,  by  the  intervention  of  carbonate  of  soda, 
has  been  formed  from  the  chloride  of  calcium  of  the  primeval 
ocean  and  deposited  as  limestone  (ante,  pages  2  and  10.) 

An  indispensable  condition  for  the  precipitation  of  carbon- 
ate of  magnesia  is  the  absence  of  chloride  of  calcium  from  the 
solutions,  and  this,  in  the  presence  of  an  excess  of  sulphates, 
is  attained  simply  by  evaporating  to  the  point  where  gypsum 
becomes  insoluble.  In  nearly  all  river  and  spring  waters  bicar- 
bonate of  lime  is  present  in  a  large  proportion,  and  is  often  the 
most  abundant  salt.  We  have  shown  that,  when  mingled  with 
a  solution  containing  sulphate  of  magnesia,  it  gives  rise,  by 
double  decomposition,  to  bicarbonate  of  magnesia  and  sulphate 
of  lime.  By  the  evaporation  of  such  a  solution,  the  latter  salt, 

*  For  descriptions  of  these  various  waters  of  Canada,  see  the  following 
essay  in  this  volume. 


86  CHEMISTRY  OF  DOLOMITES  AND   GYPSUMS.         [VIII. 

being  the  less  soluble,  is  first  deposited  in  the  form  of  gyp- 
sum, while  the  magnesian  carbonate  is  only  separated  after  fur- 
ther evaporation ;  when,  provided  the  supply  of  bicarbonate  of 
lime  still  continues,  the  two  carbonates  may  fall  down  in  a  state 
of  intermixture.  In  this  way  sediments  will  be  formed  con- 
taining the  elements  of  dolomite  or  of  magnesite. 

The  solution  of  magnesian  bicarbonate  remaining  after  the 
deposition  of  gypsum  from  the  solution  possesses,  as  we  have 
seen,  the  power  of  decomposing  chloride  of  calcium,  and,  when 
deprived  of  a  portion  of  its  carbonic  acid  by  evaporation,  reacts 
in  a  similar  manner  with  a  solution  of  sulphate  of  lime. 
In  this  way,  an  influx  of  sea-water  into  the  basin  from 
which  gypsum,  and  perhaps  a  portion  of  magnesian  carbonate, 
has  already  been  deposited,  would  give  rise  to  a  precipitate  of 
carbonate  of  lime,  like  the  tufaceous  limestones  whose  occur- 
rence with  gypsum  and  dolomites  has  been  already  noticed. 
In  basins  which,  like  the  salt-lagoons  of  Bessarabia  on  the 
shores  of  the  Black  Sea,  receive  occasional  additions  of  sea- 
water,  and  deposit  every  summer  large  amounts  of  salt  (Bischof, 
Lehrbuch,  II.  1717),  the  influx  of  waters  containing  bicarbonate 
of  lime  would  give  rise  to  the  formation  of  beds  of  gypsum, 
alternating  with  dolomites  or  magnesian  marls  and  rock-salt. 

We  have  already  referred  to  the  analyses  of  certain  rivers  in 
which  the  sulphates  are  more  abundant  than  the  chlorides. 
Thus,  in  the  Ehine,  near  Bonn,  according  to  Bischof,  we  have 
for  100,000  parts  of  the  water,  17.08  of  solid  matters,  of  which 
1.23  are  sulphate  of  lime,  and  1.81  sulphate  of  magnesia,  with 
only  1.45  of  chloride  and  8.37  of  carbonate  of  lime  ;  in  the 
Danube,  near  Vienna,  the  predominance  of  sulphates  is  still 
more  marked.  The  waters  of  the  Arve,  in  the  month  of  Feb- 
ruary, gave  to  Tingry,  for  100,000  parts,  24.5  of  solid  matters, 
of  which  6.5  were  sulphate  of  lime,  6.2  sulphate  of  magnesia, 
and  8.3  carbonate  of  lime,  with  only  1.5  of  chlorides.  Now, 
as  in  river-waters  there  is  always  present  an  excess  of  carbonic 
acid,  and  as  bicarbonate  of  lime  and  sulphate  of  magnesia  in 
solution  are  mutually  decomposed,  these  waters,  which  are  to  be 
regarded  as  solutions  of  sulphate  of  lime  and  bicarbonate  of 


VIII.]         CHEMISTRY  OF  DOLOMITES  AND  GYPSUMS.  87 

magnesia,  would,  by  their  evaporation,  yield  gypsum  and 
magnesian  carbonate,  which  would  appear  as  portions  of  a 
fresh-water  formation,  like  those  of  Aix  and  Auvergne. 

The  similar  decomposition  of  soluble  sulphates  by  bicarbon- 
ates  of  baryta  and  strontia  will  explain  the  formation  of  heavy 
spar  and  celestine,  and  their  frequent  association  with  gypsif- 
erous  rocks. 

As  to  the  native  sulphur  which  is  often  associated  both  with 
epigeuic  and  sedimentary  gypsums,  it  has  doubtless  in  every 
case  been  formed,  as  Breislak  long  since  indicated,  by  the  de- 
composition of  sulphuretted  hydrogen.  It  is  well  known  that 
alkaline  and  earthy  sulphates  are  reduced  to  sulphurets  by  or- 
ganic matters,  with  the  aid  of  heat,  or  even  at  ordinary  temper- 
atures, in  presence  of  water.  To  the  decomposition  of  these 
sulphurets  by  water  and  carbonic  acid  we  are  to  ascribe  not 
only  the  sulphuretted  hydrogen  of  solfataras  (which,  by  its 
oxidation  under  different  conditions,  gives  rise  either  to  free 
sulphur  or  to  sulphuric  acid  and  to  gypsum  by  epigeuesis),  but 
also  the  sulphuretted  hydrogen  which  appears  in  springs  and  in 
stagnant  waters,  where  the  sulphur  produced  by  the  decompo- 
sition of  the  gas  is  often  mingled  with  sedimentary  gypsums.* 
(Bischof,  Lehrbuch,  II.  139  -  185.)  Bischof  has  also  suggested 
the  decomposition  of  chloride  of  magnesium  by  alkaline  or  earthy 
sulphurets  as  a  source  of  sulphuretted  hydrogen  and  hydrate  of 
magnesia,  into  which  sulphuret  of  magnesium  is  readily  resolved 
in  the  presence  of  water.  (Chemical  Geology,  I.  16.)  If  a  salt 
of  calcium  were  present,  this  reaction  could  only  take  place  in 
the  absence  of  carbonic  acid,  for  carbonate  of  magnesia  is  incom- 
patible with  chloride  of  calcium.  The  direct  reduction  and 
decomposition  of  sulphate  of  magnesia  by  organic  matter  and 
carbonic  acid  may,  however,  yield  sulphuretted  hydrogen  and 
carbonate  of  magnesia,  and  thus,  in  certain  cases,  give  rise  to 
magnesian  sediments. 

In   the  preceding  sections,  we  have   supposed   the   waters 
mingling  with  the  solution  of  sulphate  of  magnesia  to  contain 

*  On  certain  modes  of  decomposition  of  the  sulphates,  see  Jacquemin,  Comp- 
tea  Rendus,  June  14,  1858. 


88  CHEMISTEY  OF  DOLOMITES  AND   GYPSUMS.         [VIII. 

no  other  bicarbonate  than  that  of  lime ;  but  bicarbonate  of 
soda  is  often  present  in  large  proportion  in  natural  waters,  and 
the  addition  of  this  salt  to  sea-water  or  other  solutions  con- 
taining chlorides  and  sulphates  of  lime  and  magnesia  will,  as 
we  have  shown,  separate  the  lime  as  carbonate,  and  give  rise 
to  liquids,  which,  without  being  concentrated  brines,  as  in  the 
previous  case,  will  contain  sulphate  of  magnesia,  but  no  lime- 
salts.  A  further  portion  of  bicarbonate  of  soda  will  produce 
bicarbonate  of  magnesia,  by  the  evaporation  of  whose  solutions, 
as  before,  hydrated  carbonate  of  magnesia  would  be  deposited, 
mingled  with  the  carbonate  of  lime  which  accompanies  the  alka- 
line salt,  and  in  the  case  of  the  waters  of  alkaline  springs,  the 
compounds  of  iron,  manganese,  zinc,  nickel,  lead,  copper,  arsenic, 
chrome,  arid  other  metals,  which  springs  of  this  kind  still  bring 
to  the  surface.  In  this  way  the  metalliferous  character  of  many 
dolomites  is  explained. 

As  the  separation  of  magnesian  carbonate  from  saline  waters 
by  the  action  of  bicarbonate  of  soda  does  not  suppose  a  very 
great  degree  of  concentration,  we  may  conceive  this  process 
to  go  on  in  basins  where  animal  life  exists,  and  thus  explain 
the  origin  of  fossiliferous  magnesian  limestones  like  those  of 
Dudswell  and  the  palaeozoic  formations  of  the  western  United 
States,  whose  organic  remains,  as  I  am  informed  by  Professor 
James  Hall  of  Albany,  are  generally  such  as  indicate  a  shallow 
sea.  To  the  intervention  of  carbonate  of  soda  is,  I  conceive, 
to  be  referred  the  origin  of  all  those  dolomites  which  are  not 
accompanied  by  gypsums,  and  which  make  up  by  far  the  larger 
part  of  the  magnesian  limestones  ;  nor  will  the  dolomites  thus 
derived  be  necessarily  marine,  for  the  same  reagent,  with  waters 
like  those  of  the  Danube  and  Arve,  would  give  rise  to  dolomites 
and  magnesites  in  fresh-water  formations,  which  would  not  be 
accompanied  by  gypsums. 

To  the  first  stage  of  the  reaction  between  alkaline  bicarbon- 
ates  and  sea-water  I  am  disposed  to  ascribe  the  formation  of 
certain  deposits  of  carbonate  of  lime  which,  although  included 
in  fossiliferous  formations,  are,  unlike  most  of  their  associated 
limestones,  not  of  organic  origin,  but  have  the  characters  of  a 


VIII.]         CHEMISTRY  OF  DOLOMITES  AND   GYPSUMS.  89 

chemical  precipitate  of  nearly  pure  carbonate  of  lime,  in  which 
are  often  imbedded  silicified  shells  and  corals.*  It  is  not  per- 
haps easy  in  all  cases  to  distinguish  between  such  precipitates, 
which  may  assume  a  concretionary  structure  (see  on  this  ques- 
tion Bischof,  Chemical  Geology,  I.  428),  and  those  deposits 
which,  like  travertines,  have  been  formed  from  subterranean 
springs.  In  neither  case,  however,  should  they  be  confounded 
with  the  tufaceous  limestones  mentioned  above. 

The  union  of  the  mingled  carbonates  of  lime  and  magnesia 
to  form  dolomite  is  attended  with  contraction,  which,  in  case 
the  sediment  was  already  somewhat  consolidated,  would  give 
rise  to  fissures  and  cavities  in  the  mass.  Should  the  dolomitic 
strata  be  afterwards  exposed  to  the  action  of  infiltrating  carbon- 
ated waters,  the  excess  of  carbonate  of  lime  and  any  calcareous 
fossils  would  be  removed,  leaving  the  mass  still  more  porous, 
and  with  only  the  moulds  of  the  fossils.  Insoluble,  however, 

*  The  large  proportion  of  dissolved  silica  which  many  river-waters  contain 
appears  in  sedimentary  deposits,  not  only  replacing  fossils  and  forming 
concretions  and  even  beds  of  flint,  chert,  and  jasper,  but  also  in  a  crystal- 
line state,  as  is  seen  in  the  crystallized  quartz  often  associated  with  these 
amorphous  varieties,  and  in  some  beds  of  sandstone  which  are  made  up  en- 
tirely of  small  crystals  of  quartz.  Elie  de  Beaumont  long  since  called  atten- 
tion to  the  crystalline  nature  of  certain  sandstones  which,  as  Daubree  has 
remarked,  could  not  have  been  derived  from  the  disintegration  of  any  known 
rock  ;  and  Mr.  J.  Brainard,  at  the  meeting  of  the  American  Association  for 
the  Advancement  of  Science,  held  at  Cleveland  in  1860,  insisted  upon  the 
crystalline  character  of  the  grains  composing  certain  sandstones  in  Ohio,  as 
evidence  that  these  were  chemical  deposits.  He  however  fell  into  the  error  of 
supposing  that  all  sandstones  and  even  quartzose  conglomerates  have  had  a 
like  origin,  while  the  latter  and  the  greater  part  of  the  former  are  undoubtedly 
mechanical  deposits  from  the  ruins  of  pre-existing  quartzose  and  granitic 
rocks. 

These  crystallized  sands,  according  to  Daubree,  are  met  with  in  beds  in  the 
sandstone  of  the  Vosges,  the  variegated  sandstone  (Triassic  and  Permian), 
and  in  the  tertiary  of  the  Paris  basin  and  elsewhere.  Other  sands  are  made 
up  of  globules  of  chalcedony,  apparently,  like  the  crystallized  sands,  a  chemical 
deposit,  and  associated  with  oolitic  iron  ores  in  the  lias,  and  with  glauconite 
grains  in  the  green-sand.  (Daubree,  Recherches  sur  le  Striage  des  Roches, 
etc.,  Ann.  des  Mines,  1857.)  We  may  here  mention  the  so-called  gaize  from 
the  green-sand  of  the  Ardennes,  which  gave  to  Sauvage  56.0  p.  c.  of  amor- 
phous soluble  silica  mixed  with  quartz-sand  and  glaucouite.  (Bischof,  Lehr- 
buch,  I.  768-811.) 


90  CHEMISTRY  OF  DOLOMITES  AND   GYPSUMS.         [VIII. 

as  it  appears  to  be  at  ordinary  temperatures,  the  filling  up  by  it 
of  such  cavities  both  in  magnesian  and  in  pure  limestones,  not 
less  than  its  deposition  in  veins  and  druses,  indicates  that  dolo- 
mite is  under  certain  conditions  soluble  in  water. 


Conclusions. 

1.  The  action  of  solutions  of  bicarbonate  of  soda  upon  sea- 
water  separates  in  the  first  place  the  whole  of  the  lime  in  the 
form  of  carbonate,  and  then  gives  rise  to  a  solution  of  bicar- 
bonate of  magnesia,  which  by  evaporation  deposits   hydrous 
magnesian  carbonate. 

2.  The  addition  of  solutions  of  bicarbonate  of  lime  to  sul- 
phate of  soda  or  sulphate  of  magnesia  gives  rise  to  bicarbonates 
of  these  bases,  together  with  sulphate  of  lime,  which  latter  may 
be  thrown  down  by  alcohol.     By  the  evaporation  of  a  solution 
containing  bicarbonate  of  magnesia  and  sulphate  of  lime,  either 
with  or  without  sea-salt,  gypsum  and  hydrous  carbonate  of  mag- 
nesia are  successively  deposited. 

3.  When  the  hydrous  carbonate  of  magnesia  is  heated  alone 
under  pressure,  it  is  converted  into  magnesite  ;  but  if  carbonate 
of  lime  be  present,  a  double  salt  is  formed,  which  is  dolomite. 

4.  Solutions  of  bicarbonate  of  magnesia  decompose  chloride 
of  calcium,  and,  when  deprived  of  their  excess  of  carbonic  acid 
by  evaporation,  even  solutions  of  gypsum,  with  separation  of 
carbonate  of  lime. 

5.  Dolomites,  magnesites,   and  magnesian  marls  have  had 
their  origin  in  sediments  of  magnesian  carbonate  formed  by 
the  evaporation  of  solutions  of  bicarbonate  of  magnesia.     These 
solutions  have  been  produced  either  by  the  action  of  bicarbon- 
ate of  lime  upon  solutions  of  sulphate  of  magnesia,  in  which 
case  gypsum  is  a  subsidiary  product,  or  by  the  decomposition 
of  solutions  of  sulphate  or  chloride  of  magnesium  by  the  waters 
of  rivers  or  springs  containing  bicarbonate  of  soda.     The  sub- 
sequent action  of  heat  upon  such  magnesian  sediments,  either 
alone  or  mingled  with  carbonate  of  lime,  has  changed  them 
into  magnesite  or  dolomite. 


VIIL]         CHEMISTRY  OF  DOLOMITES  AND  GYPSUMS.  91 

SUPPLEMENT. 

[In  reference  to  the  formation  of  dolomite,  as  indicated  above, 
in  3,  it  was  shown  in  the  continuation  of  these  researches,  pub- 
lished, as  already  mentioned,  in  1866,  that  the  result  was  best 
attained  when  a  mixture  of  the  two  carbonates,  precipitated 
together  and  still  amorphous,  was  gradually  heated  with  water, 
under  pressure,  to  a  temperature  of  120°  C. ;  and  the  question 
was  raised,  whether  all  the  deposits  of  dolomite  in  nature  have 
been  thus  heated,  or  "whether  there  are  yet  unknown  con- 
ditions under  which  the  double  carbonate,  dolomite,  can  be 
formed  at  lower  temperatures." 

As  to  the  reaction  noticed  in  2,  it  was  found  that  the  partial 
loss  of  carbonic  acid  during  the  spontaneous  evaporation  of 
solutions  holding  gypsum  and  bicarbonate  of  magnesia  often 
renders  the  results  of  experiments  very  imperfect,  but  that 
the  conditions  of  complete  success  in  the  separation  of  gypsum 
from  such  solutions  are  attained  when  the  evaporation  is  con- 
ducted in  an  atmosphere  containing  a  large  proportion  of  car- 
bonic-acid gas  (ante,  page  43).  This  result  was  first  described 
in  a  note  to  the  American  Association  for  the  Advancement  of 
Science,  in  August,  1866.  (Canadian  Naturalist,  III.  123.) 

I  have  found  in  solutions  prepared  with  sulphate  of  mag- 
nesia and  bicarbonate  of  lime,  as  in  2,  the  proportion  of 
sulphate  of  lime  to  the  water  as  1  :  404  and  1  :  413 ;  while  a 
saturated  solution  of  gypsum  in  pure  water  at  16°  C.  con- 
tained 1  :  372,  which  nearly  agrees  with  Giese's  determination 
of  1  :  380.  Taking,  as  a  mean  of  these,  1  :  400,  we  have  for  a 
litre  of  water  2.50  grammes  of  anhydrous  sulphate  of  lime, 
equal  to  3.16  of  gypsum.  From  a  solution  prepared  as  above 
I  have,  in  a  successful  experiment,  separated  by  evaporation 
in  the  open  air  1.18  grammes  of  gypsum  to  the  litre,  leaving 
in  solution  an  equivalent  of  magnesian  bicarbonate.  Of  the 
latter  compound,  Bineau  obtained  solutions  in  which  11.2 
grammes  of  magnesia  (equal  to  23.5  of  monocarbonate)  were 
dissolved  in  a  litre  of  water  with  very  nearly  two  equiva- 
lents of  carbonic  acid;  and  I  have  found  it  easy  to  prepare 


92  CHEMISTRY  OF  DOLOMITES  AND  GYPSUMS.         [VIII. 

solutions,  permanent  in  the  air,  holding,  as  bicarhonate,  21.0 
grammes  of  monocarbonate  of  magnesia  to  the  litre;  so  that 
the  solubility  of  carbonate  of  magnesia  under  these  conditions 
is  about  nine  times  as  great  as  that  of  sulphate  of  lime.  (Amer. 
Jour.  Science  (2),  XXVIII.  pages  170-178. 

The  fact  that  the  separation  of  the  carbonate  of  magnesia 
necessary  for  the  production  of  dolomites  and  magnesites  re- 
quires the  absence  of  chloride  of  calcium  from  the  waters  in 
which  it  is  deposited,  —  whether  this  carbonate  is  generated 
by  the  reaction  of  bicarbonate  of  lime  on  sulphate  of  magnesia 
(with  simultaneous  production  of  gypsum),  or  by  the  interven- 
tion of  bicarbonate  of  soda,  —  and  that  in  both  cases  isolated 
and  evaporating  basins  are  indispensable  conditions  of  the 
formation  and  deposition  of  this  magnesian  carbonate,  was 
clearly  pointed  out,  as  above,  in  1859.  The  legitimate  de- 
ductions from  this  as  to  the  geographical  and  climatic  condi- 
tions of  regions  during  the  formation  of  magnesian  limestones 
were  further  insisted  upon  in  a  paper  upon  the  Geology  of 
Southwestern  Ontario,  in  1868,  and  again  in  1871,  in  paper 
XIII.  of  the  present  volume.  (See  also  ante,  page  74.) 

It  was  not,  however,  I  believe,  till  1871  that  these  views 
of  mine  found  recognition,  when  Professor  A.  C.  Ramsay,  by 
the  investigation  of  the  magnesian  limestone  of  the  Permian 
in  England,  was  led  to  reject  as  untenable  the  notion  held  by 
Sorby  (and  by  others),  that  this  was  once  an  ordinary  lime- 
stone of  organic  origin  subsequently  impregnated  with  magne- 
sian carbonate  under  conditions  not  explained ;  and  to  con- 
clude that  the  carbonates  of  lime  and  magnesia  of  which  it 
is  composed  had  been  "  deposited  simultaneously  by  the  con- 
centration of  solutions  due  to  evaporation,"  "  in  an  inland  salt 
lake."  To  this  view,  as  he  informs  us,  he  was  led  by  physi- 
cal considerations,  and  by  the  depauperated  condition  of  the 
organic  remains  contained  in  these  strata,  without  being,  at 
the  time,  aware  that  I  had  twelve  years  previously  announced 
the  same  conclusions  for  all  magnesian  limestones,  and  estab- 
lished them  on  chemical  grounds.  (Quar.  Geol.  Jour.,  1871, 
page  249.)] 


IX. 

THE  CHEMISTRY  OF  NATURAL 
WATERS. 

This  paper  appeared  in  the  American  Journal  of  Science  for  March,  July,  and  Sep- 
tember, 1865.  In  reprinting  it,  the  original  tables  of  analyses  have  been  omitted,  and 
in  their  place  a  few  typical  analyses  only  are  given.  Some  other  omissions  have  been 
made  for  the  sake  of  brevity,  and  a  few  notes  added.  In  a  Supplement  I  have  given 
the  results  of  the  examination  of  additional  waters  of  the  first  class,  some  of  them 
remarkable  for  the  great  amount  of  soluble  sulphides  present ;  and  in  an  Appendix, 
details  and  results  of  experiments  on  the  porosity  of  rocks.  Both  the  Supplement  and 
the  Appendix  are  from  the  Report  of  the  Geological  Survey  of  Canada  for  1863  -  66. 

IT  is  proposed  to  divide  this  essay  into  three  parts,  in  the 
first  of  which  will  be  considered  some  general  principles  which 
must  form  the  basis  of  a  correct  chemical  history  of  natural 
waters.  The  second  part  will  embrace  a  series  of  chemical 
analyses  of  mineral  waters  from  the  palaeozoic  rocks  of  the 
Champlain  and  St.  Lawrence  and  Ottawa  basins,  together  with 
some  river-waters  ;  and  the  third  part  will  consist  chiefly  of 
deductions  and  generalizations  from  these  analyses. 

I. 

CONTENTS  OF  SECTIONS.  —  1.  Atmospheric  waters ;  2,  3.  Results  of  vege- 
table decay;  4-7.  Action  on  rocky  sediments;  8.  Action  on  iron-oxide  ; 
9.  Solution  of  alumina;  10.  Reduction  of  sulphates;  11.  Kaolin izat ion ; 
12.  Decay  of  silicates;  13.  Origin  of  carbonate  of  soda;  14.  Bischof  s 
view  rejected ;  15,  16.  Porosity  of  rocks,  and  their  contained  saline 
waters  ;  17.  Saliferous  strata;  18.  Action  of  carbonate  of  soda  on  saline 
waters;  19.  Origin  of  sulphate  of  magnesia;  20,  21.  Mitscherlich's  view 
rejected;  22,23.  Salts  from  evaporating  sea- water ;  composition  of  ancient 
seas;  origin  of  carbonate  of  lime;  24-27.  Origin  of  gypsum,  carbonate  of 
magnesia,  and  dolomite ;  28.  Waters  from  oxidized  sulphurets ;  29.  Origin 
of  free  sulphuric  and  hydrochloric  acids ;  30.  Of  hydrosulphuric  and  boric 
acids;  31.  Of  carbonic-acid  gas  ;  32.  Of  ammoniacal  salts  ;  33-35.  Classi- 
fication of  mineral  waters. 

§  1.  The  solvent  powers  of  water  are  such  that  this  liquid 
is  never  met  with  in  nature  in  a  perfectly  pure  state ;  even 


94  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

meteoric  waters  hold  in  solution,  besides  nitrogen,  oxygen, 
carbonic  acid,  ammonia,  and  nitrous  compounds,  small  quan- 
tities of  solid  matters  which  were  previously  suspended  in  the 
form  of  dust  in  the  atmosphere.  After  falling  to  the  earth, 
these  same  waters  become  still  further  impregnated  with  for- 
eign elements  of  very  variable  nature,  according  to  the  con- 
ditions of  the  surface  on  which  they  fall. 

§  2.  Atmospheric  waters,  coming  in  contact  with  decaying 
vegetable  matters  at  the  earth's  surface,  take  from  them  two 
classes  of  soluble  ingredients,  organic  and  inorganic.  The 
waters  of  many  streams  and  rivers  are  colored  brown  with  dis- 
solved organic  matter,  and  yield,  when  evaporated  to  dryness, 
colored  residues,  which  carbonize  by  heat.  This  organic  sub- 
stance, in  some  cases  at  least,  is  azotized,  and  similar,  if  not 
identical,  in  composition  and  properties  with  the  apocrenic 
acid  of  Berzelius.  The  decaying  vegetation,  at  the  same  time 
that  it  yields  a  portion  of  its  organic  matter  in  a  soluble  form, 
parts  with  the  mineral  or  cinereal  elements  which  it  had  re- 
moved from  the  soil  during  life.  The  salts  of  potassium,  cal- 
cium, and  magnesium,  the  silica  and  phosphates,  which  are  so 
essential  to  the  growing  plant,  are  liberated  during  the  process 
of  decay  ;  and  hence  we  find  these  elements  almost  wanting  in 
peat  and  coal.  (See  on  this  point  the  analyses  by  Vohl  of 
peat,  peat-moss,  and  the  soluble  matters  set  free  during  its 
decay;  Ann.  der  Chem.  und  Pharm.,  CIX.  185.  Also  Liebig, 
analysis  of  bog-water,  Letters  on  Modern  Agriculture,  p.  44  ; 
and  in  the  second  part  of  this  paper,  the  analysis  of  the  water 
of  the  Ottawa  River.) 

§  3.  At  the  same  time  an  important  change  is  effected  in 
the  gaseous  contents  of  the  atmospheric  waters.  The  oxygen 
which  they  hold  in  solution  is  absorbed  by  the  decaying 
organic  matter,  and  replaced  by  carbonic  acid ;  while  any 
nitrates  or  nitrites  which  may  be  present  are  by  the  same 
means  reduced  to  the  state  of  ammonia  (Kuhlmann).  By  thus 
losing  oxygen,  and  taking  up  a  readily  oxidizable  organic  mat- 
ter, these  waters  become  reducing  instead  of  oxidizing  media 
in  their  further  progress. 


IX.]        CHEMISTRY  OF  NATURAL  WATERS.         95 

§  4.  We  have  thus  far  considered  the  precipitated  atmos- 
pheric waters  as  remaining  at  the  earth's  surface ;  but  a  great 
portion  of  them,  sooner  or  later  in  their  course,  come  upon  per- 
meable strata,  by  which  they  are  absorbed,  and  in  their  sub- 
terranean circulation  undergo  important  changes.  The  effect 
of  ordinary  argillaceous  strata  destitute  of  neutral  soluble  salts 
may  be  first  examined.  Between  such  sedimentary  strata  and 
the  waters  charged  with  organic  and  mineral  matters  from 
decaying  vegetation  there  are  important  reactions.  The  com- 
position of  these  waters  is  peculiar;  they  contain,  relatively 
to  the  sodium,  a  large  amount  of  potassium  salts,  besides 
notable  quantities  of  silica  and  phosphates,  in  addition  to 
the  dissolved  organic  matters  and  the  earthy  carbonates,  and 
in  many  cases  ammoniacal  salts  and  nitrates  or  nitrites.  The 
sulphuric  acid  and  chlorine  are  moreover  not  sufficient  to  neu- 
tralize the  alkalies,  which  are  perhaps  in  part  combined  with 
silica  or  with  an  organic  acid. 

§  5.  The  experiments  of  Way,  Voelcker,  and  others  have 
shown  that  when  such  waters  are  brought  into  contact  with 
argillaceous  sediments,  they  part  with  their  potash,  ammo- 
nia, silica,  phosphoric  acid,  and  organic  matter,  which  remain 
in  combination  with  the  soil ;  while,  under  ordinary  condi- 
tions at  least,  neither  soda,  lime,  magnesia,  sulphuric  acid, 
nor  chlorine  are  retained.  This  power  of  the  soil  appears, 
from  the  experiments  of  Eichhorn,  to  be  in  part  due  to  the 
action  of  hydrated  double  aluminous  silicates ;  and  the  pro- 
cess is  one  of  double  exchange,  an  equivalent  of  lime  or  soda 
being  given  up  for  the  potash  and  ammonia  retained.  The 
phosphates  are  probably  retained  in  combination  with  alumina 
or  peroxide  of  iron,  and  the  silica  and  organic  matters  also 
enter  into  insoluble  combinations.  It  follows  from  these  re- 
actions thai  the  surface-waters  charged  with  the  products  of 
vegetable  decay,  after  having  been  brought  in  contact  with 
argillaceous  sediments,  retain  little  else  than  sulphates,  chlorides, 
or  carbonates  of  soda,  lime,  and  magnesia.  In  this  way  the 
mineral  matters  required  for  the  growth  of  plants,  and  by 
them  removed  from  the  soil,  are  again  restored  to  it;  and 


96  CHEMISTRY  OF  NATURAL  WATERS.  IX.] 

from  this  reaction  results  the  small  proportion  of  potash-salts 
in  the  waters  of  ordinary  springs  and  wells  as  compared 
with  river- waters.  From  the  waters  of  rivers,  lakes,  and  seas, 
aquatic  plants,  again  take  up  the  dissolved  potash,  phosphates, 
and  silica ;  and  the  subsequent  decay  of  these  plants  in  con- 
tact with  the  ooze  of  the  bottom,  or  on  the  shores,  again 
restores  these  elements  to  the  earth.  See  a  remarkable  essay, 
by  Forchhammer,  on  the  composition  of  fucoids,  and  their 
geological  relations,  Jour,  fur  Prakt.  Chem.,  XXXVI.  388. 

§  6.  The  observations  of  Eichhorn  upon  the  reaction  be- 
tween solutions  of  chlorides  and  pulverized  chabazite,  which, 
as  a  hydrated  silicate  of  alumina  and  lime,  may  perhaps  be 
taken  as  a  representative  of  the  hydrous  double  silicates  in 
the  soil,  show  that  these  substitutions  of  protoxide  bases  are 
neither  complete  nor  absolute.  It  would  appear,  on  the  con- 
trary, that  there  takes  place  a  partial  exchange  or  a  partition 
of  bases  according  to  their  respective  affinities.  Thus  the  nor- 
mal chabazite,  in  presence  of  a  solution  of  chloride  of  sodium, 
exchanges  a  large  portion  of  its  lime  for  soda ;  but  if  the  re- 
sulting soda-compound  be  placed  in  a  solution  of  chloride  of 
calcium,  an  inverse  substitution  takes  place,  and  a  portion 
of  lime  enters  again  into  the  silicate,  replacing  an  equivalent 
of  soda  ;  while,  by  the  action  of  a  solution  of  chloride  of  potas- 
sium, both  lime  and  soda  are,  to  a  large  extent,  replaced  by 
potash.  In  like  manner,  chabazite,  in  which,  by  the  action 
of  a  solution  of  sal-ammoniac,  a  part  of  the  lime  has  been 
replaced  by  ammonia,  will  give  up  a  portion  of  the  ammonia, 
not  only  to  solutions  of  chlorides  of  potassium  and  sodium,  but 
even  to  chloride  of  calcium.  It  results  from  these  mutual  de- 
compositions that  there  is  a  point  where  a  chabazite  contain- 
ing both  lime  and  soda,  or  lime  and  ammonia,  would  remain 
unchanged  in  mixed  solutions  of  the  corresponding  chlorides, 
the  affinities  of  the  rival  bases  being  balanced.*  Inasmuch, 
however,  as  the  proportions  of  ammonia  and  potash  in  natural 
waters  are  usually  small  when  compared  with  the  amounts  of 
lime  and  soda  existing  in  the  form  of  hydro-silicates  in  the 

*  Amer.  Jour.  Science  (2),  XXVIII.  72. 


IX.]  CHEMISTRY  OP  NATURAL  WATERS.  97 

soil,  the  result  of  these  affinities  is  an  almost  complete  elimina- 
tion of  the  ammonia  and  potash  from  infiltrating  waters. 

§  7.  That  the  replacement  of  one  base  by  another  in  this 
way  is  not  complete  is  shown  moreover  by  the  experiments 
of  Liebig,  Deherain,  and  others,  who  have  observed  that  a 
solution  of  gypsum  removes  from  soils  a  certain  amount  of 
potash- salt,  which  was  insoluble  in  pure  water.  In  this  way 
gypseous  waters  may  also  acquire  portions  of  sulphate  of  soda 
from  silicates. 

It  is  not  certain  that  all  the  above  reactions  observed  for 
chabazite  are  applicable  without  modification  to  the  double 
hydro-aluminous  silicates  of  sedimentary  strata.  Were  such 
the  case,  important  changes  might,  in  certain  conditions,  be 
effected  in  the  composition  of  saline  waters.  Thus  in  presence 
of  a  great  amount  of  a  hydrous  silicate  of  lime  and  alumina, 
solutions  of  chloride  of  sodium  might  acquire  a  considerable 
amount  of  chloride  of  calcium ;  but  it  is  probable  that  these 
reactions,  however  important  they  may  be  in  relation  to  the 
soil,  and  to  surface-waters  with  their  feeble  saline  impregna- 
tion, have  at  present  but  little  influence  on  the  composition 
of  the  stronger  saline  waters.  It  is  however  not  impossible 
that  the  action  of  the  ancient  sea- waters,  holding  a  large  amount 
of  chloride  of  calcium,  upon  the  hydrated  and  half-decomposed 
feldspars  which  constituted  the  clays  of  the  period,  may  have 
given  rise  to  those  double  silicates  which  formed  the  lime-soda 
feldspars  so  abundant  in  the  Labrador  series. 

§  8.  The  reactions  just  described  assume  an  importance  in 
the  case  of  waters  impregnated  with  soluble  matters  from  vege- 
table decay  ;  and  in  this  event,  another  and  not  less  important 
class  of  phenomena  intervenes,  due  to  the  deoxidizing  power 
of  the  dissolved  organic  matter.  By  the  action  of  this  upon 
the  insoluble  peroxide  of  iron  set  free  from  the  decomposition 
of  ferruginous  minerals  and  disseminated  in  the  sediments,  pro- 
toxide of  iron  is  formed,  which  is  soluble  both  in  carbonic  acid 
and  in  the  excess  of  the  organic  (acid)  matter.  By  this  means 
not  only  are  great  quantities  of  iron  dissolved,  but  masses  of 
sediments  are  sometimes  entirely  deprived  of  iron-oxide,  and 
5  G 


98  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

thus  beds  of  white  clay  and  sand  are  formed.  The  waters  thus 
charged  with  proto-salts  of  iron  absorb  oxygen  when  exposed 
to  the  air,  and  then  deposit  the  metal  as  hydrated  peroxide, 
which,  when  the  organic  matter  is  in  excess,  carries  down  a 
greater  or  less  proportion  of  it  in  combination.  Such  organic 
matters  are  rarely  absent  from  limonite,  and  in  some  specimens 
of  ochre  amount  to  as  much  as  fifteen  per  cent.*  The  condi- 
tions under  which  hydrous  peroxide  of  manganese  is  often 
found  are  very  similar  to  those  of  hydrous  peroxide  of  iron 
with  which  it  is  so  frequently  associated ;  and  there  is  little 
doubt  that  oxide  of  manganese  may  be  dissolved  by  a  process 
like  that  just  pointed  out.  A  portion  of  manganese  has  been 
observed  in  the  soluble  matters  from  decaying  peat-moss ;  and 
it  seems  to  be  generally  present  in  small  quantities  with  iron 
in  surface-waters. 

§  9.  There  is  reason  to  believe  that  alumina  is  also,  under 
certain  conditions,  dissolved  by  waters  holding  organic  acids. 
The  existence  of  pigotite,  a  native  compound  of  alumina  with 
an  organic  acid,  and  the  occasional  association  of  gibbsite  with 
limonite,  point  to  such  a  reaction.  That  it  is  not  more  abun- 
dant in  solution,  is  due  to  the  fact,  that,  unlike  most  other 
metallic  oxides,  alumina,  instead  of  being  separated  in  a  free 
state  by  the  slow  decomposition  of  its  silicious  compounds, 
remains  in  combination  with  silica.  The  formation  of  bauxite, 
a  mixture  of  hydrate  of  alumina  with  variable  proportions  of 
hydrous  peroxide  of  iron,  which  forms  extensive  beds  in  the 
tertiary  sediments  of  the  great  Mediterranean  basin,  indicates 
a  solution  of  alumina  on  a  grand  scale,  and  perhaps  owes  its 
origin  to  the  decomposition  of  solutions  of  native  alum  by 
alkaline  or  earthy  carbonates.  Emery,  a  crystalline  anhydrous 
form  of  alumina,  has  doubtless  been  formed  in  a  similar  man- 
ner. (American  Journal  Science  (2),  XXXIT.  287,  and  ante, 
page  13.)  The  existence  in  many  localities  of  an  insoluble  sub- 
sulphate  of  alumina,  websterite,  in  layers  and  concretionary 
masses  in  tertiary  clays,  evidently  points  to  such  a  process. 
Compounds  consisting  chiefly  of  hydrated  alumina  are  frequently 

*  Geology  of  Canada,  p.  512. 


IX.]        CHEMISTRY  OF  NATURAL  WATERS.         99 

found  in  fissures  of  the  chalk  in  England.  On  the  absence 
of  free  hydrated  alumina  from  soils,  see  Miiller,  cited  as  above 
(2),  XXXV.  292. 

§  10.  The  organic  matter  dissolved  by  the  surface-waters 
serves  to  reduce  to  the  condition  of  sulphurets  the  various  sol- 
uble sulphates  which  it  takes  up  at  the  same  time  or  meets 
with  in  its  course.  These  sulphurets,  decomposed  by  carbonic 
acid,  which  is  in  part  derived  from  the  atmosphere,  and  in  part 
from  the  oxidation  of  the  carbon  of  the  organic  matter,  give 
rise  to  alkaline  and  earthy  carbonates  on  the  one  hand,  and  to 
sulphuretted  hydrogen  on  the  other.  In  this  way,  under  the 
influence  of  a  somewhat  elevated  temperature,  are  generated 
sulphurous  waters,  whether  of  subterranean  springs,  or  of  trop- 
ical sea-marshes  and  lagoons.  The  reaction  between  the  sul- 
phurets thus  formed  and  the  salts  or  oxides  of  iron,  copper,  and 
similar  metals  which  may  be  present,  gives  rise  to  metallic 
sulphurets.  The  decomposition  of  sulphuretted  hydrogen  by 
the  oxygen  of  the  air  produces  native  sulphur ;  with  which  are 
generally  found  associated  sulphates  of  lime  and  strontia.  By 
virtue  of  these  reactions,  soluble  sulphates  of  lime  and  magnesia 
may  be  completely  eliminated  from  waters,  the  bases  as  insol- 
uble carbonates,  and  the  sulphur  as  sulphuretted  hydrogen,  free 
sulphur,  or  a  metallic  sulphuret.  Moreover,  as  Forchharnmer 
has  pointed  out  in  the  paper  already  cited,  sulphuret  of  potas- 
sium in  the  presence  of  ferruginous  clays  is  also  completely 
separated  from  solution,  the  sulphur  as  sulphuret  of  iron,  and 
the  alkali  as  a  double  aluminous  silicate. 

§  11.  We  have  thus  far  considered  the  composition  of  sur- 
face-waters as  modified  by  the  decay  of  vegetation,  or  by  the 
reactions  between  the  matters  derived  from  this  source  and  the 
permeated  sediments.  Not  less  important  however  than  the 
elements  thus  removed  by  substitution  from  sedimentary  strata 
are  those  which  are  liberated  by  the  slow  decomposition  of  the 
minerals  composing  these  sediments. 

It  has  long  been  known  that  in  the  transformation  of  a  feld- 
spar into  kaolin,  the  double  silicate  of  alumina  and  alkali  takes 
up  a  portion  of  water,  and  is  resolved  into  a  hydrous  silicate  of 


100  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

alumina ;  while  the  alkali,  together  with  a  definite  portion  of 
silica,  is  separated  in  a  soluble  state.  The  feldspar,  an  anhy- 
drous double  salt  formed  at  an  elevated  temperature,  has  a 
tendency  under  certain  conations  to  combine,  at  a  lower  tem- 
perature, with  a  portion  of  water,  and  break  up  into  two  sim- 
pler silicates.  Daubree  has  moreover  shown  that  when  kaolin 
is  exposed  to  a  heat  of  400°  C.  in  presence  of  a  soluble 
silicate  of  potash,  the  two  silicates  unite  and  regenerate  feld- 
spar. These  reactions  are  completely  analogous  to  those  pre- 
sented by  very  many  other  double  salts,  ethers,  amides,  and 
similar  compounds.  The  preliminary  conditions  of  this  con- 
version of  feldspar  into  kaolin  and  a  soluble  alkaline  silicate, 
however,  still  require  investigation.  It  is  known  that  while 
some  feldspathic  rocks  appear  almost  unalterable,  others  con- 
taining the  same  species  of  feldspar  are  found  converted  to  a 
depth  of  many  feet  from  the  surface  into  kaolin.  This  chemi- 
cal alteration,  according  to  Fournet,  is  always  preceded  by  a 
mechanical  change  of  the  feldspar,  which  first  becomes  opaque 
and  friable,  and  is  thus  rendered  permeable  to  water.  He  con- 
ceives this  alteration  to  be  molecular,  and  to  be  connected  with 
the  passage  of  the  silicate  into  a  dimorphous  or  allotropic  con- 
dition. * 

§  12.  The  researches  of  Ebelman  on  the  alterations  of  various 
rocks  and  minerals  have  thrown  considerable  light  on  the  rela- 
tions of  sediments  and  natural  waters. t  From  the  analyses  of 
basaltic  and  similar  rocks,  which  include  silicates  of  lime, 
magnesia,  iron,  and  manganese  in  the  forms  of  pyroxene,  horn- 
blende, and  olivine,  and  which  undergo  a  slow  and  superficial 
decomposition  under  atmospheric  influences,  it  appears  that 
during  the  process  of  decay  the  greater  part  of  the  lime  and 
magnesia  is  removed,  together  with  a  large  proportion  of  silica. 


*  [Annales  de  Cliimie  (2),  LV.  225.  It  is  a  subject  for  inquiry  how  far 
such  changes  are  recent,  and  whether  all  feldspars  found  thus  decomposed 
are  not  portions  which  have  been  preserved  to  us  from  a  remote  antiquity, 
when  atmospheric  agencies  more  potent  than  those  of  the  present  day  were 
at  Work.  Ante,  page  10.] 

f  Ebelman,  Recueil  des  Travaux,  II.  1-79. 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  101 

It  was  found,  moreover,  that  in  the  case  of  a  rock  apparently 
composed  of  labradorite  and  pyroxene,  the  removal  of  the  lime 
and  magnesia  from  the  decomposed  portion  was  much  more 
complete  than  that  of  the  alkalies  ;  showing  thutf  the  compara- 
tively greater  stability  of  the  feldspathic  element.  The  decom- 
position of  the  feldspar  in  these  mixed  rocks  is  however  at 
length  effected,  and  the  final  result  approximates  to  a  hydrous 
silicate  of  alumina  or  clay.  This  slow  decomposition  of  sili- 
cates of  protoxide-bases  appears  to  be  due  to  the  action  of  car- 
bonic acid,  which,  removing  the  lime  and  magnesia  as  carbon- 
ates, liberates  the  silica  in  a  soluble  form ;  while  the  iron  and 
manganese,  passing  to  a  state  of  higher  oxidation,  remain 
behind,  unless  the  action  of  organic  matters  intervenes  to  give 
them  solubility. 

§  1 3.  Notwithstanding  the  complete  decomposition,  resulting 
in  the  production  of  kaolin,  to  which  orthoclase,  in  common 
with  the  triclinic  feldspars  (and  some  other  feldspathides,  such 
as  the  scapolites,  beryl,  and  leucite),  is  subject,  it  is  to  be  noticed, 
that  under  ordinary  atmospheric  conditions  orthoclase  appears 
less  liable  to  change  than  the  lime-soda  feldspars  such  as 
albite,  oligoclase,  and  labradorite.  Weathered  surfaces  of  these 
become  covered  with  a  thin,  soft,  white,  and  opaque  crust 
from  decomposition,  while  the  surfaces  of  orthoclase  under 
similar  conditions  still  preserve  their  hardness  and  translucency. 
A  gradual  process  of  this  kind  is  constantly  going  on  in  the 
feldspathic  matters  which  form  a  large  proportion  of  the  me- 
chanical sediments  of  all  formations  ;  and  in  deeply  buried 
strata  is  not  improbably  accelerated  by  the  elevation  of  temper- 
ature. The  soluble  alkaline  silicate  resulting  from  this  process 
is  in  most  cases  decomposed  by  carbonates  of  lime  and  magnesia 
in  the  sediments,  giving  rise  to  silicates  of  these  bases  (which 
are  for  the  greater  part  separated  in  an  insoluble  state),  and  to 
carbonate  of  soda.  Only  in  rare  cases  does  potash  appear  in 
large  proportion  among  the  soluble  salts  thus  liberated  from, 
sediments,  partly  because  soda-feldspars  are  more  subject  to 
chanpre,  and  partly  from  the  fact  that  potash-salts  would  be 
separated  from  the  percolating  waters  in  virtue  of  the  reactions 


102  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

mentioned  in  §  5.  Hence  it  happens  that  apart  from  the 
neutral  soda-salts  of  extraneous  origin,  waters  permeating  sedi- 
ments containing  alkaliferous  silicates  generally  bring  to  the 
surface  little  more  than  soda  combined  with  carbonic  and 
sometimes  with  boric  acid,  and  carbonates  of  lime  and  magne- 
sia with  small  portions  of  silica. 

§  14.  This  explanation  of  the  decomposition  of  alkaliferous 
silicates  and  of  the  origin  of  carbonate  of  soda  is  opposed  to 
the  view  of  Bischof,  who  conceives  that  carbonic  acid  is  the 
chief  agent  in  decomposing  feldspathic  minerals.*  The  sol- 
vent action  of  waters  charged  with  carbonic  acid  is  undoubted, 
as  shown  by  various  experimenters,  especially  by  the  Messrs. 
Bogers,t  but  this  acid  is  not  always  present  in  the  quantities 
required.  The  proportion  of  it  in  atmospheric  waters  is  so 
inadequate  that  it  becomes  necessary  to  suppose  some  subter- 
ranean source  of  the  gas,  which  is  by  no  means  a  constant 
accompaniment  of  natron-springs.  A  copious  evolution  of 
carbonic  acid  is  observed  in  the  vicinity  of  the  lake  of  Laach, 
where  the  alkaline  waters  studied  by  Bischof  occur.  J  The 
same  thing  is  met  with  in  many  other  localities  of  such  springs, 
among  which  may  be  mentioned  the  region  around  Saratoga, 
where  saline  waters  containing  carbonate  of  soda,  and  highly 
charged  with  carbonic  acid,  rise  in  abundance  from  the  lower 
palaeozoic  strata ;  but  farther  northward,  along  the  valleys  of 
Lake  Champlain  and  the  St.  Lawrence,  similar  alkaline-saline 
waters,  which  abound  in  the  continuation  of  the  same  geologi- 
cal formations,  are  not  at  all  acidulous.  From  this  the  conclu- 
sion seems  justifiable  that  the  production  of  carbonate  of  soda 
is  a  process,  in  some  cases  at  least,  independent  of  the  presence 
of  free  carbonic  acid.  In  this  connection,  it  is  well  to  recall 
the  solvent  action  of  pure  water  on  alkaliferous  silicates,  as 
shown  more  especially  by  Bunsen,  and  also  by  Damour,  who 
found  that  distilled  water  at  temperatures  much  below  212° 
takes  up  from  silicates  like  palagonite  and  calcined  mesotype 

*  Bischof,  Chem.  Geol.,  II.  131. 
f  Ainer.  Jour.  Sci.  (2),  V.  401. 
J  Bischof,  Lehrbuch,  I.  357-363. 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  103 

comparatively  large  amounts  both  of  silica  and  alkalies.  (Ann. 
Chim.  et  Phys.  (3),  XIX.  481.) 

[The  view  advanced  in  §  13  is  to  be  understood  of  the 
subterranean  decomposition  of  alkaliferous  silicated  minerals, 
the  results  of  which  appear  in  waters  like  some  noted  further 
on  in  §  67,  where,  from  a  deficiency  of  carbonic  acid,  parts  of 
the  bases  are  present  as  silicates,  as  in  the  solutions  prepared 
by  Damour.  At  the  same  time  it  is  clear  that  carbonic  acid 
greatly  favors  the  process,  as  seen  in  the  experiments  of  Rogers, 
and  has  played  a  most  important  part  in  the  subaerial  decom- 
position of  crystalline  rocks,  from  which,  as  Ebelman  showed, 
have  been  removed  not  only  the  alkalies  of  the  feldspar,  but 
the  lime  and  magnesia  of  the  hornblende.  The  absence  of 
any  excess  of  carbonic  acid  in  many  alkaline -saline  waters,  as 
noticed  in  §  66,  appears  a  conclusive  argument  for  the  view  set 
forth  in  §  13,  that  the  subterranean  decomposition  of  alkalifer- 
ous sediments  takes  place  independent  of  the  intervention  of 
carbonic  acid.] 

§  15.  Another  and  an  important  source  of  mineral  impregna- 
tion to  waters  exists  in  the  soluble  salts  enclosed  in  sedimentary 
strata,  both  in  the  solid  state  and  in  aqueous  solution,  and  for 
the  most  part  of  marine  origin.  In  order  to  form  some  con- 
ception of  the  amount  of  saline  matters  which  may  be  contained 
in  a  dissolved  state  in  the  rocky  strata  of  the  earth,  I  have 
made  numerous  experiments  to  determine  the  porosity  of  various 
rocks  ;  a  few  of  the  results,  so  far  as  regards  the  lower  palae- 
ozoic formations  of  the  Xew  York  system  (in  which  occur  the 
mineral  waters  named  in  the  last  section),  are  here  given.  For 
further  details,  and  for  a  table  of  results,  the  reader  is  referred 
to  the  Appendix  to  this  paper  in  the  present  volume.  The 
volume  of  water  enclosed  in  100  volumes  of  the  various  rocks 
having  been  determined,  it  was  found  for  three  specimens  of  the 
Potsdam  sandstone  to  equal  2.26-2.71,  and  for  three  others  of 
the  same  rock,  much  more  porous,  6.94  —  9.35.  For  four  speci- 
mens of  the  crystalline  dolomite  which  makes  up  the  so-called 
Calciferous  sand-rock  the  volume  was  equal  to  1.89-2.53,  and 
for  two  other  varieties  of  the  same  rock,  5.90-7.22. 


104  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

§  16.  If  we  take  for  the  Potsdam  sandstone  the  mean  of  the 
first  three  trials,  giving  2.5  per  cent  for  the  volume  of  water 
which  it  is  capable  of  holding  in  its  pores,  we  find  that  a  thick- 
ness of  100  feet  of  it  would  contain  in  every  square  mile,  in 
round  numbers,  70,000,000  cubic  feet  of  water;  an  amount 
which  would  supply  a  cubic  foot  (over  seven  gallons)  a  minute 
for  more  than  thirteen  years.  The  observed  thickness  of  the 
Potsdam  sandstone  in  the  district  of  Montreal  varies  from  200 
to  700  feet,  and  a  mean  of  500  feet  may  be  assumed.  To  this 
are  to  be  ad^ed  300  feet  for  the  Calciferous  sand-rock,  whose 
capacity  for  water  may  be  taken,  like  the  Potsdam  sandstone, 
at  2.5  per  cent.  We  have  thus  in  each  square  mile  of  these 
formations,  wherever  they  lie  below  the  water-level,  a  volume 
of  490,000,000  cubic  feet  of  water,  equal  to  a  supply  of  a 
cubic  foot  per  minute  for  106  years.  The  capacity  of  the 
800  feet  of  Chazy  and  Trenton  limestones  which  succeed  these 
lower  formations  may  be  fairly  taken  at  one  half  that  of  those 
just  named.  But  it  is  unnecessary  to  multiply  such  calcula- 
tions :  enough  has  been  said  to  show  that  these  sedimentary 
strata  include  in  their  pores  great  quantities  of  water,  which 
was  originally  that  of  the  palaeozoic  ocean.  These  strata,  through- 
out the  palaeozoic  basin  of  the  St.  Lawrence,  are  now  for  the 
greater  part  beneath  the  sea-level ;  nor  is  there  any  good  rea- 
son for  supposing  them  to  have  ever  been  elevated  much  above 
their  present  horizon.  Wells  and  borings  sunk  in  various 
places  in  these  rocks  show  them  to  be  still  filled  with  bitter 
saline  waters  ;  but  in  regions  where  these  rocks  are  inclined 
and  dislocated,  surface-waters  gradually  replace  these  saline 
waters,  which,  in  a  mixed  and  diluted  state,  appear  as  mineral 
springs.  These  saline  solutions,  other  things  being  equal,  will 
be  better  preserved  in  limestones  or  argillaceous  rocks  than  in 
the  more  porous  and  permeable  sandstones. 

§  17.  But  besides  the  saline  matters  thus  disseminated  in  a 
dissolved  state  in  ordinary  sedimentary  rocks,  there  are  great 
volumes  of  saliferous  strata,  properly  so  called,  charged  with 
ths  results  of  the  evaporation  of  ancient  sea-basins.  These 
strata  enclose  not  only  gypsum  and  rock-salt,  but  in  some 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  105 

regions  large  quantities  of  the  double  chloride  of  potassium  and 
magnesium,  carnallite ;  and  in  others  sulphate  of  soda,  sulphate 
of  magnesia,  and  complex  sulphates  like  bloedite  and  polyhal- 
lite.  Besides  these  crystalline  salts,  the  mother-liquors  con- 
taining the  more  soluble  and  uncrystallizable  compounds  may 
also  be  supposed  to  impregnate,  in  some  cases,  the  sediments 
of  these  saliferous  formations.  The  conditions  under  which 
these  various  salts  are  deposited  from  sea-water,  and  their  rela- 
tions to  the  composition  of  the  ocean  in  earlier  geological 
periods,  are  reserved  for  consideration  in  §  22.  Infiltrating 
waters  remove  from  these  saliferous  strata  their  soluble  ingre- 
dients; which,  together  with  the  ancient  sea-waters  of  other 
sedimentary  rocks,  give  rise  to  the  various  neutral  saline 
waters;  while  the  mingling  of  these  in  various  proportions 
with  the  alkaline  waters  whose  origin  has  been  described  in 
§  13,  produces  intermediate  classes  of  waters  of  much  interest. 

§  18.  I  have  elsewhere  described  the  results  of  a  series  of 
experiments  on  the  mutual  action  of  the  waters  of  these  two 
classes.*  When  a  dilute  solution  of  bicarbonate  of  soda  is 
gradually  added  to  a  solution  which,  like  sea-water,  contains, 
besides  chloride  of  sodium,  the  chlorides  and  sulphates  of  calcium 
and  magnesium,  the  greater  part  of  the  lime  separates  as  car- 
bonate, carrying  down  with  it  only  from  one  to  three  hun- 
dredths  of  carbonate  of  magnesia ;  a  portion  of  lime  however 
remaining  in  -solution  as  bicarbonate.  When  the  chloride  of 
calcium  is  wholly  decomposed,  the  magnesian  salt  is  attacked 
in  its  turn,  and  there  finally  results  a  solution  in  which  the 
whole  of  the  earthy  chlorides  are  replaced  by  chloride  of  sodium. 
A  further  addition  of  the  solution  of  bicarbonate  of  soda  gives 
them  the  character  of  alkaline-saline  waters ;  which  moreover 
contain  an  abundance  of  earthy  carbonates. 

§  19.  In  the  saline  waters  just  considered,  chlorides  generally 
predominate,  the  sulphates  being  small  in  amount,  and  often 
altogether  wanting.  Some  exceptions  to  this  are  however  met 
with ;  for  apart  from  waters  impregnated  with  gypsum,  whose 
origin  is  readily  understood,  there  are  others  in  which  sulphate 

*  American  Journal  Science  (2),  XXVIII.  170. 
5* 


106  CHEMISTRY   OF  NATURAL  WATERS.  [IX. 

of  soda  or  sulphate  of  magnesia  enter  largely.  The  soda-salt 
may  sometimes  be  formed  by  the  reaction  between  solution  of 
gypsum  and  natriferous  silicates  referred  to  in  §  7,  or  by  the 
decomposition  of  gypsum  by  solution  of  carbonate  of  soda; 
while  in  other  cases  its  origin  will  probably  be  found  in  the 
natural  deposits  of  sulphates,  such  as  glauberite,  thenardite, 
and  glauber-salt,  which  occur  in  saliferous  rocks.  A  similar 
origin  is  probable  for  many  of  those  springs  in  which  sulphate 
of  magnesia  predominates.  This  salt  also  effloresces  abundant- 
ly in  a  nearly  pure  form  upon  certain  limestones,  and  is  in 
some  cases  due  to  the  action  of  sulphates  from  decomposing 
pyrites  upon  magnesian  carbonate  or  silicate.  In  by  far  the 
greater  number  of  cases,  however,  its  appearance  is  unconnected 
with  any  such  process  ;  and  is,  according  to  Mitscherlich,  due 
to  a  reaction  between  dolomite  and  dissolved  gypsum. 

§  20.  In  support  of  this  view,  it  was  found  by  the  chemist 
just  named  that  when  a  solution  of  sulphate  of  lime  was  made 
to  filter  for  some  time  through  pulverized  magnesian  limestone, 
it  was  decomposed  with  the  formation  of  carbonate  of  lime  and 
sulphate  of  magnesia.  This  reaction  I  have  been  unable  to 
verify.  A  solution  of  gypsum  in  distilled  water  was  made  to 
percolate  slowly  through  a  column  of  several  inches  of  finely 
powdered  dolomite,  and  after  ten  filtrations,  occupying  as  many 
days,  no  perceptible  amount  of  sulphate  of  magnesia  had  been 
formed.  Solutions  of  gypsum  were  then  digested  for  many 
months  with  pulverized  dolomite,  and  also  with  crystalline 
carbonate  of  magnesia,  but  with  similar  negative  results ;  nor 
did  the  substitution  of  a  solution  of  chloride  of  calcium  lead 
to  the  formation  of  any  soluble  magnesian  salt.  Solutions  of 
gypsum  were  then  impregnated  with  carbonic  acid,  and  allowed 
to  remain  in  contact  with  pulverized  dolomite  and  with  magne- 
site,  as  before,  during  six  months  of  the  warm  season,  when 
only  inappreciable  traces  of  magnesia  were  taken  into  solution. 
These  experiments  show  that  no  decomposition  of  dissolved 
gypsum  is  effected  by  native  carbonate  of  magnesia,  or  by  the 
double  carbonate  of  lime  and  magnesia,  at  ordinary  tem- 
perature. 


IX. J        CHEMISTRY  OF  NATURAL  WATERS.        107 

§  21.  I  find,  however,  that  hydrated  carbonate  of  magnesia 
readily  and  completely  decomposes  a  solution  of  gypsum  when 
agitated  with  it,  with  formation  of  carbonate  of  lime  and 
sulphate  of  magnesia ;  and  the  same  result  is  produced  by  the 
native  hydrate  of  magnesia  when  mingled  with  a  solution  of 
gypsum  in  presence  of  carbonic  acid.  Now  there  may  be 
dolomites  which  contain  an  admixture  of  hydro-carbonate  of 
magnesia,  as  there  certainly  are  others  which,  like  predazzite, 
are  penetrated  with  hydrate  of  magnesia.*  The  reaction 
between  solutions  of  gypsum  and  such  magnesian  limestones 
(with  the  intervention,  in  the  case  of  predazzite,  of  atmospheric 
carbonic  acid)  would  suffice  to  explain  the  results  obtained  by 
Mitscherlich,  and  the  appearance  in  certain  cases  of  sulphate 
of  magnesia  as  an  efflorescence  on  dolomites.  In  the  exper- 
iments above  described,  the  nearly  pure  crystalline  dolomites 
from  the  Guelph  and  Niagara  formations  were  made  use  of. 

§  22.  When  sea-water  is  exposed  to  spontaneous  evapora- 
tion, the  lime  which  it  contains  separates  in  the  form  of  sul- 
phate, gypsum  being  but  sparingly  soluble  in  a  concentrated 
brine,  and  the  greater  portion  of  the  chloride  of  sodium  crystal- 
lizes out  in  a  nearly  pure  state.  The  mother-liquor  of  specific 
gravity  1.24,  having  lost  about  four  fifths  of  its  chloride  of 
sodium,  still  contains  dissolved  a  large  proportion  of  sulphate 
of  magnesia.  If  the  evaporation  is  continued  at  the  ordinary 
temperature  till  a  density  of  1.32  is  attained,  about  one  half 
of  the  magnesian  sulphate  separates,  mixed  with  common  salt ; 
and  by  reducing  the  temperature  to  6°  C.,  a  large  portion  of 
pure  sulphate  of  magnesia  now  crystallizes  out.  The  further 
evaporation  of  the  remaining  liquor  by  the  heat  of  summer 
causes  the  potassium-salt  to  separate  in  the  form  of  a  hydrous 
double  chloride  of  potassium  and  magnesium,  an  artificial  car- 
iiallite.f 

[*  In  subsequent  experiments  it  was  found  that  certain  dolomites  contain  a 
little  hydrous  carbonate  of  magnesia  capable  of  decomposing  a  limited  amount 
of  solution  of  gypsum.  See  the  author,  On  Lime  and  Magnesia  Salts,  Ameri- 
can Journal  of  Science  for  July,  1866,  §§  96-101.] 

+  The  hydrous  double  chloride  of  potassium  and  magnesium,  to  which  the 
name  of  carnallite  has  been  given,  occurs  in  large  quantities  iu  the  upper 


108  CHEMISTEY  OF  NATURAL  WATERS.  [IX. 

By  varying  somewhat  the  conditions  of  temperature,  the  sul- 
phate of  magnesia  and  the  chloride  of  sodium  of  the  mother- 
liquor  undergo  mutual  decomposition,  with  the  production  of 
sulphate  of  soda  and  chloride  of  magnesium.  Hydrated  sul- 
phate of  soda  crystallizes  out  from  such  a  mixed  solution  at 
0°  C.,  and  by  reducing  the  temperature  to  — 18°  C.  the  greater 
part  of  the  sulphates  may  he  separated  in  this  form  from  the 
mother-liquor  of  1.24,  previously  diluted  with  one  tenth  of 
water ;  without  which  addition  a  mixture  of  hydrated  chloride 
of  sodium  would  separate  at  the  same  time.  If,  on  the  other 
hand,  the  temperature  of  the  mixed  solution  be  raised  above 
50°  C.,  the  sulphate  of  soda  crystallizes  out  in  the  anhydrous 
form,  as  thenardite.  By  the  spontaneous  evaporation  during 
the  heats  of  summer  of  the  mother-liquors  of  density  1.35,  a 
double  sulphate  of  potassium  and  magnesium  separates.  These 
reactions  are  taken  advantage  of  on  a  great  scale  in  Balard's 
process,  as  modified  by  Merle,*  for  extracting  salts  from  sea- 
water. 

§  23.  The  results  of  the  evaporation  of  sea-water  would 
however  be  widely  different  if  an  excess  of  lime-salt  were 
present.  In  this  case  the  whole"  of  the  sulphates  present  would 
be  deposited  in  the  form  of  gypsum  at  an  early  stage  of  the 
evaporation,  and  the  mother-liquor,  after  the  separation  of  the 
greater  part  of  the  common  salt,  would  contain  little  else  than 
the  chlorides  of  sodium,  potassium,  calcium,  and  magnesium. 

§  24.  A  consideration  of  the  conditions  of  the  ocean  in 
earlier  geological  periods  will  show  that  it  must  have  con- 
tained a  much  larger  quantity  of  lime-salts  than  at  present. 
The  alkaline  carbonates,  whose  origin  has  been  described  in 
§13,  and  which  from  the  earliest  times  have  been  flowing 

strata  of  the  saliferous  formation  of  Stassfurth  in  Germany  ;  where  it  is  as- 
sociated with  a  hydrous  double  chloride  of  calcium  and  magnesium,  tachydrite, 
and  also  with  a  sparingly  soluble  sulphate  of  magnesia,  kieserite,  which  con- 
tains a  small  and  variable  amount  of  water,  and  is  supposed  to  be,  in  its  nor- 
mal condition,  an  anhydrous  salt.  When  heated  to  redness  in  a  current  of 
steam  this  sulphate  loses  all  its  acid,  which  passes  off  undecomposed. 

*  See  my  paper  in  Amer.  Jour.  Science  (2),  XXV.  361;  also  Report  of  the 
Juries  of  the  Exhibition  of  1862,  Class  II.  page  48. 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  109 

into  the  sea,  have  gradually  modified  the  composition  of  its 
waters,  separating  the  lime  as  carbonate,  and  thus  replacing 
the  chloride  of  calcium  by  chloride  of  sodium,  as  I  have  long 
since  pointed  out  (ante,  page  2).  This  reaction  has  doubt- 
less been  the  source  of  all  the  carbonate  of  lime  in  the  earth's 
crust,  if  we  except  that  derived  from  the  decomposition  of 
calcareous  silicates.  (§12.)  In  this  decomposition  by  car- 
bonate of  soda,  as  already  described  in  §  18,  it  results  from 
the  incompatibility  of  chloride  of  calcium  with  hydrous  car- 
bonate of  magnesia,  that  the  lime  is  first  precipitated,  with 
a  little  adhering  carbonate  of  magnesia ;  and  it  is  only  when 
the  chloride  of  calcium  is  all  decomposed  that  the  magnesian 
chloride  is  transformed  into  carbonate  of  magnesia.  This  lat- 
ter reaction  can  consequently  take  place  only  in  limited  basins, 
or  in  portions  cut  off  from  the  oceanic  circulation. 

§  25.  It  follows  from  what  has  been  said  that  the  lime-salt 
may  be  eliminated  from  sea-water  either  as  sulphate  or  as  car- 
bonate. In  the  latter  case  no  concentration  is  required  ;  while 
in  the  former  the  conditions  are  two,  —  a  sufficient  proportion 
of  sulphates  to  convert  the  whole  of  the  lime  into  gypsum, 
and  such  a  degree  of  concentration  of  the  water  as  to  render 
this  insoluble.  These  conditions  meet  in  the  evaporation  of 
modern  sea-water  ;  but  the  evaporated  sea-water  of  earlier 
periods,  with  its  great  predominance  of  lime-salts,  would  still 
contain  large  amounts  of  chloride  of  calcium,  —  the  insolubility 
of  gypsum  in  this  case  serving  to  eliminate  all  the  sulphates 
from  the  mother-liquor.  Evaporation  alone,  would  not  suffice 
to  remove  the  whole  of  the  lime-salts  from  waters  in  which 
the  calcium  present  was  more  than  equivalent  to  the  sulphuric 
acid ;  but  the  intervention  of  carbonate  of  soda  would  be  re- 
quired. 

§  26.  In  concentrated  and  evaporating  waters  freed  from 
lime-salts  by  either  of  the  reactions  just  mentioned,  but  still 
holding  sulphate  of  magnesia,  another  process  may  intervene 
(ante,  page  90).  The  addition  of  a  solution  of  bicarbonate 
of  lime  to  such  a  solution  gives  rise,  by  double  decomposition, 
to  sulphate  of  lime  and  bicarbonate  of  magnesia.  The  forrnej, 


110  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

being  much  the  less  soluble  salt,  especially  in  a  strongly  saline 
liquid,  is  deposited  as  gypsum ;  and  subsequently  the  magne- 
sian  carbonate  is  precipitated  in  a  hydrous  form.  The  effect 
of  this  reaction  is  to  eliminate  from  the  sea-water  both  the 
sulphuric  acid  and  the  magnesia,  without  the  permanent  addi- 
tion to  it  of  any  foreign  element. 

§  27.  Gypsum  may  thus  be  separated  from  sea-water  by  two 
distinct  processes,  —  the  one  a  reaction  between  sulphate  of 
magnesia  and  chloride  of  calcium,  and  the  other  between  the 
same  sulphate  and  carbonate  of  lime.  The  latter,  involving  a 
separation  of  bicarbonate  of  magnesia,  can,  as  we  have  seen, 
only  take  place  when  the  whole  of  the  chloride  of  calcium  has 
been  eliminated ;  and  if  we  suppose  the  ancient  ocean,  unlike 
the  present,  to  have  contained  more  than  an  equivalent  of  lime 
for  each  equivalent  of  sulphuric  acid,  it  is  evident  that  a  lake 
or  basin  of  sea-water  free  from  lime-salts  could  only  have  been 
produced  by  the  intervention  of  carbonate  of  soda.  The  action 
of  this  must  have  eliminated  the  whole  of  the  lime  as  carbonate, 
or  at  least  have  so  far  reduced  the  amount  of  this  base  that  the 
sulphates  present  would  be  sufficient  to  separate  the  remainder 
by  evaporation  in  the  form  of  gypsum,  'and  still  leave  in  the 
mother-liquor  a  quantity  of  sulphate  of  magnesia  for  reaction 
with  bicarbonate  of  lime. 

The  source  of  the  magnesian  carbonate,  whose  union,  under 
certain  conditions,  with  the  carbonate  of  lime,  gives  rise  to 
dolomite  (ante,  page  90),  may  thus  be  due  either  to  the  re- 
action just  described  between  bicarbonate  of  lime  and  solutions 
holding  sulphate  of  magnesia,  or  to  the  direct  action  of  car- 
bonate of  soda  upon  waters  containing  magnesian  salts ;  but, 
in  either  case,  the  previous  elimination  of  the  incompatible 
chloride  of  calcium  must  be  considered  an  indispensable  pre- 
liminary to  the  production  of  the  magnesian  carbonate. 

§  28.  To  the  three  principal  sources  of  mineral  matters  in 
mineral  waters  already  enumerated,  namely,  decaying  organic 
matters,  decomposing  silicates,  and  the  soluble  saline  matters 
in  rocks,  a  few  other  minor  ones  must  be  added.  One  of  these 
is  the  oxidation  of  metallic  sulphurets,  chiefly  iron  pyrites, 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  Ill 

giving  rise  to  sulphate  of  iron,  and  more  rarely  to  sulphates 
of  copper,  zinc,  cobalt,  and  nickel ;  and  by  secondary  reactions 
to  sulphates  of  alumina,  lime,  magnesia,  and  alkalies.  This 
process  of  oxidation  is  necessarily  superficial  and  local,  but  the 
soluble  sulphates  thus  formed  have  probably  played  a  not  un- 
important part.  (§9.) 

§  29.  Besides  the  solutions  formed  by  this  last  process,  which 
contain  chiefly  neutral  and  acid  salts,  there  is  another  class  of 
waters  characterized  by  the  presence  of  free  sulphuric  or  hy- 
drochloric acid,  or  both  together.  These  acid  waters  sometimes 
occur  as  products  of  volcanic  action  ;  during  which  both  hydro- 
chloric acid  and  sulphur  are  often  evolved  in  large  quantities. 
This  latter  element  generally  comes  to  the  surface  as  sulphu- 
retted hydrogen,  which  by  the  oxidation  of  the  hydrogen  may 
deposit  its  sulphur  in  craters  and  fissures.  In  other  cases,  as 
shown  by  Dumas,  the  sulphur  and  hydrogen  may  be  slowly  and 
simultaneously  oxidized  at  a  low  temperature,  giving  rise  di- 
rectly to  sulphuric  acid.  Not  less  frequent,  however,  is  prob- 
ably the  direct  conversion,  by  combustion,  of  the  sulphuretted 
hydrogen  into  water  and  sulphurous  acid,  which,  afterwards 
absorbing  oxygen  fr6m  the  air,  is  converted  into  sulphuric 
acid. 

§  30.  The  source  of  the  hydrochloric  acid  and  the  sulphur 
of  volcanoes  is  probably  the  decomposition  of  chlorides  and  sul- 
phates at  high  temperatures.  It  is  known  that  for  the  decom- 
position of  earthy  chlorides,  water  and  an  elevated  temperature 
are  sufficient ;  and  at  a  higher  temperature,  chloride  of  sodium 
is  readily  decomposed  in  presence  of  silicious  and  aluminous 
minerals,  with  the  intervention  of  water.  Another  agency 
which  probably  comes  into  play  in  volcanic  phenomena  is  that 
of  organic  matters,  which,  reducing  the  sulphates  to  sulphurets, 
enable  the  sulphur  to  be  subsequently  disengaged  as  sulphu- 
retted hydrogen  by  the  operation  of  water,  either  with  or  with- 
out the  intervention  of  carbonic  acid  or  of  silicious  and  argilla- 
ceous matters.  Even  in  cases  where  this  reducing  action  is 
excluded,  the  ignition  of  sulphates  in  contact  with  earthy 
matters  must  liberate  the  sulphuric  acid  as  a  mixture  of  sul- 


112  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

phurous  acid  and  oxygen;  and  these  uniting  in  their  distil- 
lation upward  through  the  strata,  may  give  rise  to  springs  of 
sulphuric  acid.*  To  reactions  similar  to  those  just  noticed,  in- 
volving horates  like  stassfurthite  and  hayesine,  or  boric  silicates 
like  tourmaline,  etc.,  are  to  be  ascribed  the  large  amounts  of 
boric  acid  which  are  sublimed  in  some  volcanoes,  or  volatilized 
with  the  watery  vapor  of  the  Tuscan  auffioni. 

§  31.  The  action  of  subterranean  heat  upon  buried  strata 
containing  sulphates  and  chlorides  is  then  sufficient  to  explain 
the  appearance  of  hydrochloric  and  sulphurous  acids  and  sul- 
phur, even  without  the  intervention  of  organic  matters,  which 
are,  however,  seldom  or  never  wanting ;  whether  as  coal,  lig- 
nite, bitumen,  and  pyroschists,  or  in  a  more  divided  condition. 
The  presence  of  hydrogen  and  of  marsh-gas,  as  observed  by 
Deville  among  volcanic  products,  is  an  evidence  of  this.  The 
generation  of  marsh-gas  is,  however,  in  most  cases  clearly  un- 
connected with  volcanic  action  or  subterranean  heat. 

To  the  decomposition  of  carbonates  in  buried  strata  by  sili- 
cious  matters,  with  the  aid  of  heat,  is  to  be  ascribed  the  great 
amounts  of  carbonic-acid  gas  which  are  in  many  places  evolved 
from  the  earth,  and,  impregnating  the  infiltrating  waters,  give 
rise  to  acidulous  springs.  The  principal  sources  of  this  gas  in 
Europe  are  in  regions  adjoining  volcanoes,  either  active  or  re- 
cently extinct ;  but  their  occurrence  in  the  palaeozoic  strata  of 
the  United  States,  far  remote  from  any  evidence  of  volcanic 
phenomena  other  than  slightly  thermal  springs,  shows  that  an 
action  too  gentle  or  too  deeply  seated  to  manifest  itself  in  igne- 
ous eruptions,  may  evolve  carbonic  acid  abundantly.  The  sul- 
phuric-acid springs  of  western  New  York  and  Canada,  to  be 
described  further  on,  are  not  less  remarkable  illustrations  of  the 
same  fact.  [The  origin  of  free  carbonic  acid  in  certain  cases  is, 
however,  doubtless  to  be  found  in  the  reaction  pointed  out  fur- 
ther on  in  §  66.] 

§  32.  The  frequent  presence  of  amraoniacal  salts  in  volcanic 
exhalations  is  here  worthy  of  notice,  especially  when  consid- 
ered in  connection  with  the  rarity  of  nitric  and  ammoniacal 
*  See  the  note  to  §  22,  on  kieserite. 


IX.]         CHEMISTRY  OF  NATURAL  WATERS.        113 

compounds  in  natural  waters,  except  in  some  local  conditions, 
as  in  the  wells  of  cities,  etc.,  where  they  are  sometimes  ob- 
served in  comparatively  large  amounts.  The  explanation  of 
this  is  evident ;  for  although  nitrates  themselves  are  not  direct- 
ly removed  from  the  water,  they  are,  by  the  reducing  action  of 
organic  matters,  converted  into  ammonia,  which  is  retained  by 
the  soil.  In  consequence  of  this  affinity  the  argillaceous  strata, 
whether  of  the  present  period  or  of  older  formations,  hold  in 
a  very  fixed  form  a  considerable  quantity  of  nitrogen.  This, 
from  the  slowness  with  which  it  is  eliminated  in  the  form  of 
ammonia  under  the  influence  of  alkaline  solutions,  probably 
exists  as  an  ammoniacal  silicate.  (§  6.)  The  action  of  acids, 
however,  as  well  as  alkalies,  may  be  supposed  to  liberate  it 
from  its  combination,  and  thus  generate  the  ammoniacal  salts 
which  are  such  frequent  accompaniments  of  volcanic  phenomena. 
The  numerous  experiments  of  Delesse  show  that  ammonia,  or 
at  least  nitrogen  capable  of  being  evolved  by  heat  and  alkalies 
in  the  form  of  ammonia,  is  present  in  the  limestones,  marls, 
argillites,  and  sandstones  of  former  geological  periods,  in  quan- 
tities scarcely  inferior  to  those  in  similar  deposits  of  modern 
times,  amounting,  for  most  of  the  ancient  sedimentary  strata, 
to  from  one  to  five  thousandths  of  nitrogen ;  *  from  which  it 
will  be  seen  that  the  quantity  of  this  element  thus  retained 
in  the  rocky  strata  of  the  earth's  crust  is  very  great. 

§  33.  If  we  attempt  a  chemical  classification  of  natural 
waters  in  accordance  with  the  principles  laid  down  in  the  pre- 
ceding sections,  they  may  be  considered  under  the  following 
heads  :  — 

A.  Atmospheric  waters. 

B.  Waters  impregnated  with  the  soluble  products  of  vegetable 

decay. 

C.  "Waters  impregnated  with  the  salts  from  decomposing  felcl- 

gpathic  rocks,  and  holding  a  portion  of  carbonate  of  soda  as  a 
characteristic  ingredient. 

D.  Waters  holding  neutral  salts  of  sodium,  calcium,  or  nmgnesium 

from  strata  where  they  existed  as  solid  salts  or  in  brines  or 
bitterns. 

»  Ann.  des  Mines  (5),  XVIII.  151-523. 


114  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

E.  Waters  holding  chiefly  sulphates  from  decomposing  pyrites  ; 

copperas  and  alum- waters. 

F.  Waters  holding  free  sulphuric  or  hydrochloric  acid. 

§  34.  The  name  of  mineral  waters  is  popularly  applied  only 
to  such  as  contain  sufficient  foreign  matters  to  give  them  a 
decided  taste  ;  and  hence  the  waters  of  the  divisions  A  and  B, 
and  many  of  the  feebler  ones  of  C  and  D,  are  excluded.  Those 
of  E  and  F  have  peculiar  local  sources  ;  but  those  of  C  and  D 
are  often  associated  in  adjacent  geological  formations,  and  their 
commingling  in  various  proportions  gives  rise  to  mineral  waters 
intermediate  in  composition.  In  accordance  with  these  con- 
siderations, a  classification  of  mineral  waters  for  technical  pur- 
poses was  adopted  by  me,  in  1863,  in  the  Geology  of  Canada, 
p.  531,  including  only  those  of  C,  D,  and  F,  which  were  ar- 
ranged in  six  classes. 

I.  Saline  waters  containing  chloride  of  sodium,  often  with  large 
portions  of  chlorides  of  calcium  and  magnesium,  with  or 
without  sulphates.  The  carbonates  of  lime  and  magnesia 
are  either  wanting,  or  present  only  in  small  quantities. 
These  waters  are  generally  bitter  to  the  taste,  and  may  be 
designated  as  brines  or  bitterns. 

II.  Saline  waters  which  differ  from  the  last  in  containing,  besides 
the  chlorides  just  mentioned,  considerable  quantities  of 
carbonates  of  lime  and  magnesia.  These  waters  generally 
contain  much  smaller  proportions  of  earthy  chlorides  than 
the  first  class,  and  hence  are  less  bitter  to  the  taste. 

III.  Saline  waters  which  contain,  besides  chloride  of  sodium  and  the 

carbonates  of  lime  and  magnesia,  a  portion  of  carbonate  of 
soda. 

IV.  Waters  which  differ  from  the  last  in  containing  but  a  small 

proportion  of  chloride  of  sodium,  and  in  which  the  carbonate 
of  soda  predominates.  The  waters  of  this  class  generally 
contain  much  less  solid  matter  than  the  three  previous  classes, 
and  have  not  a  very  marked  taste  until  evaporated  to  a 
small  volume,  when  they  will  be  found,  like  the  last,  to  be 
strongly  alkaline. 

Of  these  four  classes,  I.  corresponds  to  the  division  D,  and 
IY.  to  C,  while  II.  and  III.  are  regarded  as  resulting  from 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  115 

the  admixture  of  these  in  varying  proportions.  Sulphates  are 
sometimes  present  in  these  waters,  but  never  predominate ;  in 
their  absence,  salts  of  barium  and  strontium  are  often  met  with. 
The  chlorides  are  generally,  if  not  always,  associated  with  bro- 
mides and  iodides.  Small  quantities  of  potassium-salts  are  also 
present,  while  borates,  phosphates,  silicates,  and  small  portions 
of  iron,  manganese,  and  alumina,  are  generally  present.  These 
various  waters  are  occasionally  sulphurous,  and  those  of  the 
last  three  classes  may  be  impregnated  with  carbonic  acid. 

V.  The  fifth  class  includes  acid  waters  remarkable  for  containing 
a  large  proportion  of  free  sulphuric  acid,  with  sulphates  of 
lime,  magnesia,  portions  of  iron,  and  alumina.  These  waters, 
which  are  characterized  by  their  sour  and  styptic  taste,  gen- 
erally contain  some  sulphuretted  hydrogen. 

VI.  The  sixth  class  includes  some  neutral  saline  waters  in  which 
the  sulphates  of  lime,  magnesia,  and  the  alkalies  predomi- 
nate ;  chlorides  being  present  only  in  small  quantities. 
These  waters,  like  the  last,  are  often  impregnated  with  sul- 
phuretted hydrogen. 

The  above  classification,  although  adopted  originally  for  the 
convenient  description  of  the  mineral  waters  of  Canada,  will,  it 
is  thought,  be  found  to  embrace  all  known  classes  of  natural 
waters,  with  the  exception  of  those  included  under  E,  and  of 
some  waters  from  volcanic  sources  holding  hydrochloric  acid. 
These  may  constitute  two  additional  classes.  In  the  first  three 
of  the  classes  above  described,  chlorides  predominate  ;  in  the 
fourth,  carbonates  ;  and  in  the  fifth  and  sixth,  sulphates.  The 
waters  of  the  first,  second,  and  sixth  classes  are  neutral ;  those 
of  the  third  and  fourth,  alkaline  ;  and  those  of  the  fifth,  acid. 


116  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

II. 

ANALYSES  OF  VARIOUS  NATURAL  WATERS. 

CONTENTS  OF  SECTIONS.  —  35,  36.  Waters  of  the  first  class ;  37.  Their  prob- 
able origin;  the  elimination  of  sulphates  ;  38.  Separation  of  lime-salts 
from  waters  ;  39.  Earthy  chlorides  in  saliferous  formations ;  brines  of 
New  York,  Michigan,  and  England .;  foot-note  on  errors  in  water-anal- 
yses ;  40.  Brines  of  western  Pennsylvania  ;  waters  in  which  chloride  of 
calcium  predominates  ;  41.  Origin  of  such  waters  ;  separation  of  magne- 
sia as  an  insoluble  silicate;  42.  Waters  of  the  second  class;  43.  Waters 
of  the  third  class  ;  44.  Waters  of  the  fourth  class  ;  Chambly  ;  45.  Other 
waters  of  the  same  class ;  Ottawa  River  ;  46.  Waters  of  Highgate  and 
Alburg ;  47.  Changes  in  the  Caledonia  waters  ;  comparative  analyses  ; 
48.  Waters  of  the  fifth  class ;  sulphuric-acid  springs  of  New  York  and 
Canada  ;  49.  Changes  in  the  composition  of  these  waters  ;  their  action  on 
calcareous  strata  ;  50.  Waters  of  the  sixth  class ;  their  various  sources ; 
51.  Examples  of  neutral  sulphated  waters ;  sulphate  of  magnesia  waters. 

[§  §  35,  36,  in  the  original  paper,  contained  descriptions  and 
analyses  of  eight  waters  of  Class  I.,  as  denned  in  §  34.  These, 
with  two  exceptions,  were  more  concentrated  than  sea-water, 
containing  from  36  to  50  and  even  68  parts  of  solid  matter  to 
1,000.  The  composition  of  three  of  them  is  here  given  :  the 
first  is  that  of  a  copious  spring  which  issues  from  the  Trenton 
limestone  at  Whitby,  Ontario ;  the  second  is  that  of  a  well 
sunk  into  the  same  limestone  at  Hallowell  not  far  from  the 
last,  and  one  of  several  wells  in  the  vicinity  similar  in  charac- 
ter, though  less  concentrated ;  and  "the  third  is  from  a  boring 
500  feet  deep,  sunk  through  the  Medina  sandstone  into  the 
underlying  Hudson  Eiver  shales  at  St.  Catherine,  Ontario.] 

Waters  of  Class  I.                                            Whitby.  Hallowell.  St.  Catherine. 

Chloride  of  sodium       .         .         .         18.9158  38.7315  29.8034 

"          potassium^      .         .         .       traces  traces  .3555 

"          calcium      .         .         .         17.5315  15.9230  14.8544 

magnesium     .         .         .       9.5437  12.9060  3.3977 

Bromide  of  sodium     .         .         .            .2482  .4685  undet. 

Iodide            " 0008  .0133  .0042 

Sulphate  of  lime .         ...  2.1923 

Carbonate  of  lime 0411          

"             magnesia.         .         .             .0227          

"             baryta  and  strontia       .      nndet.          

In  1,000  parts     ....         46.3038         68.0423        50.6075 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  117 

§  37.  The  waters  of  the  first  class  contain,  besides  chloride 
of  sodium  and  a  little  chloride  of  potassium,  large  quantities  of 
the  chlorides  of  calcium  and  magnesium,  amounting  together, 
in  several  cases,  to  more  than  one  half  the  solid  contents  of  the 
water.  Sulphates  are  either  absent,  or  occur  only  in  small 
quantities,  and  the  same  is  true  of  earthy  carbonates.  Salts  of 
baryta  and  strontia  are  sometimes  present,  while  the  propor- 
tions of  bromides  and  iodides,  though  variable,  are  often  con- 
siderable. 

In  the  large  amount  of  magnesian  chloride  which  they  con- 
tain, these  waters  resemble  the  bittern  or  mother-liquor  which 
remains  after  the  greater  part  of  the  chloride  of  sodium  has 
been  removed  from  sea-water  by  evaporation.  The  bitterns 
from  modern  seas,  however,  differ  in  the  constant  presence  of 
sulphates,  and  in  containing,  when  sufficiently  concentrated, 
only  traces  of  lime.  The  reason  of  this,  as  already  pointed  out 
in  §  22,  is  to  be  found  in  the  fact  that  in  the  waters  of  the 
present  ocean  the  sulphates  are  much  more  than  equivalent  to 
the  lime,  so  that  this  base  separates  during  evaporation  as 
gypsum.*  But  as  shown  in  §  23  and  §  24,  the  waters  of  the 
ancient  seas,  which  held  in  the  form  of  chloride  of  calcium 
the  greater  part  of  the  lime  since  deposited  as  carbonate,  must 
have  yielded  by  evaporation  bitterns  containing  a  large  pro- 
portion of  chloride  of  calcium.  Such  is  the  nature  of  the  brines 
whose  analyses  are  given  above,  and  such  we  suppose  to  have 
been  their  origin.  The  complete  absence  of  sulphates  from 
many  of  these  waters  points  to  the  separation  of  large  quantities 
of  earthy  sulphates  in  the  Cambrian  strata  from  which  these 
saline  springs  issue ;  and  the  presence  in  many  of  the  dolo- 
mitic  beds  of  the  Calciferous  sand-rock  of  small  masses  of  gyp- 
sum abundantly  disseminated  is  an  evidence  of  the  elimination 
of  the  sulphates  by  evaporation.  The  frequent  occurrence  of 
crystalline  masses  of  sulphate  of  strontian  in  the  Chazy  and 
Black  River  limestones  of  this  region  is  also  to  be  noted  as 
another  means  by  which  the  sulphates  were  separated  from  the 
waters  of  the  palaeozoic  seas.  From  the  proportions  of  chloride 
*  See  further  on  this  point,  Bischof,  Chem.  Geology,  I.  413. 


118  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

of  sodium,  varying  from  about  one  third  to  more  than  two  thirds 
of  the  solid  contents  of  the  above  waters,  it  is  apparent  that  in 
most  cases  the  process  of  evaporation  had  gone  so  far  as  to 
separate  a  part  of  the  common  salt ;  and  thus  successive  strata 
of  this  ancient  saliferous  formation  must  be  impregnated  with 
solid  or  dissolved  salts  of  unlike  composition.  The  mingling 
of  these  in  varying  proportions  affords  the  only  apparent  ex- 
planation of  the  differences  which  appear  in  the  relative  amounts 
of  the  several  chlorides  in  waters  from  the  same  region,  and 
even  from  adjacent  sources. 

§  38.  The  great  solubility  of  chloride  of  calcium  renders  it 
difficult  to  suppose  its  separation  from  the  mother-liquors  so  as 
to  be  deposited  in  a  solid  state  in  the  strata.*  The  same  re- 
mark applies  to  chloride  of  magnesium.  It  is  however  to  be 
remarked  that  the  double  chloride  of  potassium  and  magne- 
sium (carnallite)  is  decomposed  by  deliquescence  into  solid 
chloride  of  potassium  and  a  solution  of  chloride  of  magne- 
sium ;  and  thus  strata  like  those  which  at  Stassfurth  contain 
large  quantities  of  carnallite  (§  22),  might  give  rise  to  solu- 
tions of  magnesian  chloride.  This,  however,  would  require  the 
presence  of  a  large  amount  of  chloride  of  potassium  in  the 
early  seas.  It  appears  from  the  analyses  above  referred  to  that 
the  chloride  of  magnesium  sometimes  surpasses  in  amount  the 
chloride  of  calcium ;  and  sometimes,  on  the  contrary,  is  equal 
to  only  one  half  -or  one  fourth  of  the  latter  salt.  While  it  is 
not  impossible  that  the  predominance  of  the  magnesian  chloride 
in  some  waters  may  be  traced  to  the  decomposition  of  carnal- 
lite,  it  is  undoubtedly  in  most  cases  connected  with  the  action 
of  solutions  of  carbonate  of  soda ;  the  effect  of  which,  as  already 
pointed  out,  is  to  first  separate  the  soluble  lime-salt  as  carbon- 
ate, leaving  to  a  subsequent  stage  the  magnesian  chloride. 
(§18.)  As  this  reaction  replaces  the  calcium-salt  by  chloride 
of  sodium,  it  might  be  expected  that  there  would  be  an  increase 
in  the  amount  of  the  latter  salt  in  the  water  wherever  the 
magnesian  chloride  predominates,  did  we  not  remember  that 

*  [A  hydrated  double  chloride  of  calcium  and  magnesium  (tachydrite)  lias 
since  been  found  at  Stassfurth.] 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  119 

evaporation  Separates  it  from  the  water  in  the  solid  form  ;  and 
that  the  two  processes,  one  of  which  replaces  the  chloride  of 
calcium  by  chloride  of  sodium,  while  the  other  eliminates  the 
latter  salt  from  the  solution,  might  have  been  going  on  simulta- 
neously or  alternately.  As  the  nature  of  the  waters  now  under 
consideration  shows  that  the  process  of  evaporation  had  been 
carried  so  far  as  to  separate  the  sulphate  in  the  form  of  gypsum, 
and  probably  also  a  portion  of  the  chloride  of  sodium  in  a 
solid  state,  it  is  evident  that  we  have  not  yet  the  data  necessary 
for  determining  the  composition  of  the  water  of  the  ancient 
Cambrian  ocean,  as  regards  the  proportions  of  the  sodium,  cal- 
cium, and  magnesium  which  it  held  in  solution ;  and  we  can 
only  conclude  from  these  mother-liquors,  that  the  amount  of 
the  earthy  bases  was  relatively  very  large. 

§  39.  As  already  remarked  in  §  22,  the  mother-liquor  from 
modern  sea-water  contains  no  chloride  of  calcium,  but,  on  the 
contrary,  large  quantities  of  sulphate  of  magnesia ;  the  lime  in 
the  modern  ocean  being  less  than  one  half  that  required  to 
combine  with  the  sulphate  present.  If,  however,  we  examine 
the  numerous  analyses  of  rock-salt  and  of  brines  from  various 
saliferous  formations,  we  shall  find  that  chloride  of  calcium  is 
very  frequently  present  in  both  of  them  ;  thus  supporting  the 
conclusions  already  announced  in  §  24  with  regard  to  the  com- 
position of  the  seas  of  former  geological  periods.  The  oldest 
saliferous  formation  which  has  been  hitherto  investigated  is  the 
Onondaga  Salt-group  of  the  New  York  geologists,  which  be- 
longs to  the  upper  part  of  the  Silurian  series,  and  supplies  the 
strong  brines  of  Syracuse  and  Salina  in  New  York.  These, 
notwithstanding  their  great  purity,  contain  small  proportions 
of  chlorides  of  calcium  and  magnesium,  as  shown  by  the 
analyses  of  Beck,  and  the  recent  and  careful  examinations  of 
Goessmann.  In  the  brines  of  this  region  the  solid  matters  are 
equal  to  from  14.3  to  16.7  per  cent,  and  contain  on  an  average, 
according  to  the  latter  chemist,  1.54  of  sulphate  of  lime,  0.93 
of  chloride  of  calcium,  and  0.88  of  chloride  of  magnesium  in 
100 ;  the  remainder  being  chloride  of  sodium.* 

*  Goessmann,  Reports  on  the  Brines  of  Onondaga :  Syracuse,  1862  and  1864; 
also  Report  on  the  Onondaga  Salt  Co. :  Syracuse,  1862. 


120  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

The  nearly  saturated  brines  from  the  Saginaw  valley  in 
Michigan,  which  have  their  source  at  the  base  of  the  carbonifer- 
ous series,  contain,  according  to  my  calculation  from  an  analysis 
by  Professor  Dubois,  in  100  parts  of  solid  matters  :  chloride 
of  calcium  9.81,  chloride  of  magnesium  7.61,  sulphate  of  lime 
2.20,  the  remainder  being  chiefly  chloride  of  sodium.  Another 
brine  in  the  same  vicinity  gave  to  Chilton  an  amount  of  chloride 
of  calcium  equal  to  3.76  per  cent.*  In  a  specimen  of  salt  man- 
ufactured in  this  region,  Goessmann  found  1.09  of  chloride  of 
calcium ;  and  in  two  specimens  of  salt  from  the  brines  of  Ohio, 
from  the  same  geological  horizon,  0.61  and  1.43  per  cent  of  the 
same  chloride.  The  rock-salt  from  the  lias  of  Cheshire,  accord- 
ing to  Nicol,  contains  small  cavities,  partly  filled  with  air,  and 
partly  with  a  concentrated  solution  of  chloride  of  magnesium, 
with  some  chloride  of  calcium,  t 

*  Winchell,  Amer.  Jour.  Sci.  (2),  XXXIV.  311. 

f  Edin.  Neii.  Phil.  Joxir.,  VII.  111.  The  results  of  the  analyses  by  Mr. 
Northcote  of  the  brines  of  Droitwich  and  Stoke  in  the  same  region  (L.  E.  &  D. 
Philos.  Mag.  (4),  IX.  32),  as  calculated  by  him,  show  no  earthy  chlorides  what- 
ever, and  no  carbonate  of  lime,  but  carbonates  of  soda  and  magnesia,  and  sul- 
phates of  soda  and  lime.  He  regarded  the  whole  of  the  lime  present  in  the 
water  as  being  in  the  form  of  sulphate.  If,  however,  we  replace,  in  calculating 
these  analyses,  the  carbonate  of  soda  and  sulphate  of  lime  by  sulphate  of  soda 
and  carbonate  of  lime,  we  shall  have  for  the  contents  of  these  brines:  —  chlo- 
ride of  sodium,  with  notable  quantities  of  sulphate  of  soda,  some  sulphate  of 
lime,  and  carbonates  both  of  lime  and  magnesia  ;  a  composition  which  is  more 
in  accordance  with  the  admitted  laws  of  chemical  combinations.  From  these 
results,  it  would  appear  that  the  earthy  chlorides,  which  according  to  Nicol 
are  present  in  the  rock-salt  of  this  formation,  are  decomposed  by  sulphates  in 
the  waters  which,  by  dissolving  it,  give  rise  to  the  brines. 

It  is  to  be  regretted  that  in  many  water- analyses  by  chemists  of  note,  the 
results  are  so  calculated  as  to  represent  the  coexistence  of  incompatible  salts. 
Of  the  association  of  carbonates  of  soda  and  magnesia  with  sulphate  of  lime, 
as  in  the  analysis  just  noted,  it  might  be  said  that  I  have  shown  that  it 
may  occur  in  the  presence  of  an  excess  of  carbonic  acid  (ante,  page  90).  By 
evaporation,  however,  such  solutions  regenerate  carbonate  of  lime  and  sul- 
phates of  soda  and  magnesia;  and  by  the  consent  of  the  best  chemists  these 
elements  are  to  be  represented  as  thus  combined.  But  what  shall  be  said 
when  chloride  of  magnesium,  carbonate  of  soda,  and  silicate  of  soda  are  given 
as  the  constituents  of  a  water  whose  recent  analysis  may  be  found  in  a  late 
number  of  the  Chemical  News  ;  or  when  bicarbonates  of  soda,  magnesia,  and 
lime  are  represented  as  coexisting  in  a  water  with  sulphates  and  chlorides  of 
magnesium  and  aluminum  ?  These  errors  probably  arise  from  determining  in 


IX.]        CHEMISTRY  OF  NATURAL  WATERS.        121 

§  40.  The  brines  from  the  valley  of  the  Alleghany  Eiver, 
obtained  from  borings  in  the  coal  formation,  are  remarkable  for 
containing  large  proportions  of  chlorides  of  calcium  and  magne- 
sium ;  though  the  sum  of  these,  according  to  the  analyses  of 
Lenny,  is  never  equal  to  more  than  about  one  fourth  of  the 
chloride  of  sodium.  The  presence  of  salts  of  barium  and  stron- 
tium in  these  brines,  and  the  consequent  absence  of  sulphates, 
is,  according  to  Lenny,  a  constant  character  in  this  region  over 
an  area  of  two  thousand  square  miles.  (See  Bischof,  Chem. 
Geol.,  I.  377.)  A  later  analysis  of  another  one  of  these  waters 
from  the  same  region,  by  Steiner,  is  cited  by  Will  and  Kopp, 
Jahresbericht,  1861,  p.  1112.  His  results  agree  closely  with 
those  of  Lenny.  See  also  the  analysis  of  a  bittern  from  this 
region  by  Boye.  (Amer.  Jour.  Sci.  (2),  VII.  74.)* 

These  remarkable  waters  approach  in  character  to  those  of 
Whitby  and  Hallowell;  but  in  this  the  chloride  of  sodium 
forms  only  about  one  half  the  solid  contents,  and  the  propor- 
tion of  the  chloride  of  magnesium  to  the  chloride  of  calcium  is 
relatively  much  greater  than  in  the  waters  from  western  Penn- 
sylvania, where  the  maguesian  chloride  is  equal  only  to  from 
one  third  to  one  fifth  of  the  chloride  of  calcium  ;  the  proportions 
of  the  two  being  subject  in  both  regions  to  considerable  varia- 
tions. 

In  this  connection  may  be  cited  a  water  from  Bras  d'Or  in 
the  island  of  Cape  Breton,  lately  analyzed  by  Professor  How, 
which  contains  in  1,000  parts,  chloride  of  sodium  4.901,  chloride 
of  potassium  0.650,  chloride  of  calcium  4.413,  and  chloride  of 
magnesium  only  0.638,  besides  sulphate  of  lime  0.134,  carbon- 
ates of  lime  and  magnesia  0.085,  with  traces  of  iron-oxide  and 
phosphates;  =  10.821.  (Canadian  Katuralist,  VIII.  370.) 

the  recent  water,  or  in  water  not  sufficiently  boiled,  the  lime  and  magnesia 
which  would  by  prolonged  ebullition  be  separated  as  carbonates,  together  with 
portions  of  alumina,  silica,  etc.  In  the  subsequent  calculation  of  the  analyses, 
these  dissolved  earthy  bases  being  regarded  as  sulphates  or  chlorides,  instead 
of  carbonates,  there  remains  an  excess  of  soda,  which  is  wrongly  represented 
as  carbonate,  instead  of  chloride  or  sulphate  of  sodium. 

*  [For  further  examples  of  waters  of  this  class  from  western  Ontario,  see 
the  Supplement  to  this  paper.] 


122  CHEMISTRY   OF  NATURAL  WATERS.  [IX. 

The  analyses  of  European  waters  furnish  comparatively  few  ex- 
amples of  the  predominance  of  earthy  chlorides.* 

§  41.  We  have  already  shown  in  §  38  how  the  action  of 
carbonate  of  soda  upon  sea-water  or  bittern  will  destroy  the 
normal  proportion  between  the  chlorides  of  magnesium  and 
calcium  by  converting  the  latter  into  an  insoluble  carbonate, 
and  leaving  at  last  only  salts  of  sodium  and  magnesium  in 
solution.  A  process  the  reverse  of  this  has  evidently  inter- 
vened for  the  production  of  waters  like  that  from  Cape  Breton, 
and  some  others  noticed  by  Lersch,  in  which  chloride  of  cal- 
cium abounds,  with  little  or  no  sulphate  or  chloride  of  magne- 
sium. This  process  is  probably  one  connected  with  the  forma- 
tion of  a  silicate  of  magnesia.  Bischof  has  already  insisted 
upon  the  sparing  solubility  of  this  silicate,  and  has  asserted 
that  silicates  of  alumina,  both  artificial  and  natural,  when 
digested  with  a  solution  of  magnesian  chloride,  exchange  a  por- 
tion of  their  base  for  magnesia,  thus  giving  rise  to  solutions  of 
alumina;  which,  being  decomposed  by  carbonates,  may  have 
been  the  source  of  many  of  the  aluminous  deposits  referred  to  in 
§  9.  He  also  observed  a  similar  decomposition  between  a  solu- 
tion of  an  artificial  silicate  of  lime  and  soluble  magnesian  salts. 
(Bischof,  Chem.  Geology,  I.  13  ;  also  Chap.  XXIV.)  In  repeat- 
ing and  extending  his  experiments,  I  have  confirmed  his  obser- 
vation that  a  solution  of  silicate  of  lime  precipitates  silicate  of 
magnesia  from  the  sulphate  and  the  chloride  of  magnesium  ; 
and  have  moreover  found  that  by  digestion  at  ordinary  temper- 
atures with  an  excess  of  freshly  precipitated  silicate  of  lime, 
chloride  of  magnesium  is  completely  decomposed ;  an  insoluble 
silicate  of  magnesia  being  formed,  while  nothing  but  chloride 
of  calcium  remains  in  solution.  It  is  clear  that  the  greater 
insolubility  of  the  magnesian  silicate,  as  compared  with  silicate 
of  lime,  determines  a  result  the  very  reverse  of  that  produced  by 
carbonates  with  solutions  of  the  two  earthy  bases.  In  the  one 

*  Lersch,  Hydro-Chemie,  Zweite  Auflage  :  Berlin,  1864;  vide  p.  207.  This 
excellent  work,  which  is  a  treatise  on  the  chemistry  of  natural  waters,  in  one 
volume  8vo  of  700  pages,  was  unknown  to  me  when  I  prepared  the  first  part 
of  this  essay. 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  123 

case  the  lime  is  separated  as  carbonate,  the  magnesia  remaining 
in  solution ;  while  in  the  other,  by  the  action  of  silicate  of  soda 
(or  of  lime),  the  magnesia  is  removed  and  the  lime  remains. 
Hence  carbonate  of  lime  and  silicates  of  magnesia  are  found 
abundantly  in  nature ;  while  carbonate  of  magnesia  and  sili- 
cates of  lime  are  produced  only  under  local  and  exceptional 
conditions.  It  is  evident  that  the  production  from  the  waters 
of  the  early  seas  of  beds  of  sepiolite,  talc,  serpentine,  and  other 
rocks  in  which  a  magnesian  silicate  abounds,  must,  in  closed 
basins,  have  given  rise  to  waters  in  which  chloride  of  calcium 
would  predominate. 

[§  42  of  the  original  paper  contains  descriptions  and  anal- 
yses of  eight  waters  of  Class  II.,  the  solid  contents  of  which 
vary  from  9  to  20  parts  in  1 ,000 ;  they  rarely  contain  sul- 
phates. The  three  given  below,  which  may  be  taken  as  exam- 
ples, rise  from  the  Trenton  limestone  of  the  Ottawa  and  St. 
Lawrence  valleys,  the  first  being  that  known  as  the  Intermittent 
Spring  of  Caledonia.] 


Waters  of  Class  II. 
Chloride  of  sodium 
"          potassium 
barium           . 

Caledonia. 
12.2500 
.0305 

Lanoraie. 
11.1400 
.1460 
0303 

St.  Leon. 
11.4968 
.1832 
0019 

"          strontium 
'*          calcium 
"          magnesium 
Bromide  of        " 
Iodide  of 
Carbonate  of  baiy  ta 

.2870 
.       1.0338 
.0238 
.0021 

.0185 
.2420 
.2790 
.0283 
.0052 
.0106 

.0019 
.0718 
.6636 
.0091 
.0046 

"           strontia 

.0137 

lime    . 
"          magnesia 
"          iron    . 
Silica          .... 

.1264 
.8632 
traces 
.0225 

.4520 
.4622 
traces 
0552 

.3493 
.9388 
.0145 
0865 

undet 

0145 

In  1,000  parts    . 

.     14.6393 

12.8830 

13.8365 

Specific  gravity 

1010.9 

1009.42 

1011.23 

[§43  gives  the  description  and  analysis  of  eight  waters  of 
Class  III.  which  hold  from  less  than  5  to  more  than  10  parts 


124 


CHEMISTRY  OF  NATURAL  WATERS. 


[IX. 


of  solid  matter  in  1,000.  Of  the  three  whose  analysis  is  given 
below,  the  first  rises  from  the  Chazy  formation  in  the  Ottawa 
valley,  and  the  others  from  the  Utica  and  Hudson  Eiver  for- 
mations in  the  valley  of  the  St.  Lawrence.  The  alkaline-saline 
waters  of  Caledonia,  belonging  to  the  same  class,  which  will  be 
mentioned  further  on  in  §  47,  rise  from  the  Trenton  lime- 
stone in  the  former  region.] 


Waters  of  Class  III. 

Fitzroy. 

Varennes.   I 

Jaie  du  Febvre. 

Chloride  of  sodium 

6.5325 

9.4231 

4.8234 

"          potassium 

.       .1160 

.1234 

.0610 

Bromide  of  sodium 

.0217 

-  .0126 

undet. 

Iodide  of          " 

.0032 

.0054 

undet. 

Phosphate  of  soda 

.0124 

.5885 

.1705 

1.5416 

"             baryta    . 

traces 

.0226 

traces 

"             strontia 

« 

.0140 

K 

"             lime 

.1500 

.3540 

.2180 

"             magnesia 

.       .7860 

.5433 

.4263 

iron 

traces 

.0048 



0040 

traces 

undct 

Silica 

1330 

.0465 

.2129 

In  1,000  parts 

,     8.3473 

10.7202 

7.2923 

Specific  gravity 

1006.24 

1008.15 

§  44.  Of  the  waters  of  Class.  IV.  the  first  to  be  noticed  is  one 
occurring  at  Chambly,  on  the  Richelieu  Eiver,  in  the  province 
of  Quebec.  Here,  on  a  plateau,  over  an  area  of  about  two  acres, 
the  clayey  soil  is  destitute  of  vegetation  and  impregnated  with 
alkaline  waters ;  which  in  the  dry  season  give  rise  to  a  saline 
efflorescence  on  the  partially  dried  up  and  fissured  surface.  A 
well  sunk  here  to  the  depth  of  eight  or  ten  feet  in  the  clay, 
which  overlies  the  Hudson  Eiver  formation,  affords  at  all  times 
an  abundant  supply  of  water,  which  'generally  flows  in  a  little 
stream  from  the  top  of  the  well.  Small  bubbles  of  carburetted 
hydrogen  are  sometimes  seen  to  escape  from  the  water.  The 
temperature  at  the  bottom  of  the  well  was  found  in  October, 
1861,  to  be  53°  R,  and  in  August,  1865,  to  be  nearly  54°  F. 
The  mean  temperature  of  Chambly  can  differ  but  little  from 


IX.] 


CHEMISTRY  OF  NATURAL  WATERS. 


125 


that  of  Montreal,  which  is  44.6°  F.,  so  that  this  is  a  thermal 
water.  Another  alkaline  and  saline  spring  in  the  same  parish 
has  also  a  temperature  of  53°  F.  The  water  of  the  spring  here 
described  has  a  sweetish  saline  taste,  and  is  much  relished  by 
the  cattle  of  the  neighborhood.  Three  analyses  have  been 
made  of  its  waters,  the  results  of  which  are  here  given  side  by 
side.  The  first  was  collected  in.  October,  1851 ;  the  second  in 
October,  1852  ;  and  the  third  in  August,4864,  during  a  very  dry 
season. 


Waters  of  Chambly,  Class  IV. 

I. 

II. 

III. 

Chloride  of  potassium 

undet. 

.0324 

.0182 

8689 

.8387 

.8846 

Carbonate       " 

1.0295 

1.0604 

.9820 

< 

0540 

.0380 

.0253 

« 

magnesia       .         .        . 

.0908 

.0765 

.0650 

« 

strontia    .... 

undet. 

.0045 

undet. 

• 

iron      .... 

« 

.0024 

« 

Alumina  and  phosphate 

« 

.0063 

« 

Silica       ...... 

.1220 

.0730 

.0166 

Borates,  iodides,  and  bromides     . 

undet. 

undet. 

undet. 

2.1652        2.1322 


1.9917 


In  1,000  parts. 

A  portion  of  barium  is  included  with  the  strontium  salt. 
The  water  contains  moreover  a  portion  of  an  organic  acid,  which 
causes  it  to  assume  a  bright  brown  color  when  reduced  by  evap- 
oration. Acetic  acid  gave  no  precipitate  with  the  concentrated 
and  filtered  water ;  but  the  subsequent  addition  of  acetate  of 
copper  yielded  a  brown  precipitate  of  what  was  regarded  as 
apocrenate  of  copper.  The  organic  matter  of  this  and  of  many 
other  mineral  springs  has  probably  a  superficial  origin.  The 
carbonic  acid  was  determined  in  the  third  analysis,  and  was 
equal  in  two  trials  to  .903  and  .905.  The  neutral  carbonates 
in  this  water  require  .452  parts  of  carbonic  acid. 

[§§  45,  46,  give  the  analyses  of  six  more  waters  of  Class 
IY.,  none  of  which  are  as  highly  charged  with  mineral  sub- 
stances as  that  of  Chambly,  though  holding  from  0.34  to  1.55 
parts  of  solid  matter  to  1,000.  All  of  these  waters  are  found 
in  the  valleys  of  the  St.  Lawrence  and  of  Lake  Champlain, 
and  are  believed  to  rise  from  the  Utica  or  Hudson  River  shales. 


126  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

The  analyses  of  the  three  given  below  may  be  taken  as  addi- 
tional examples  of  this  class.  That  of  St.  Ours  is  remarkable 
for  a  large  proportion  of  potassium-salts,  about  twenty-five  per 
cent  of  the  alkalies,  determined  as  chlorides,  being  chloride  of 
potassium.] 

Waters  of  Class  IV.                                                 St.  Ours.  Joly.  Nicolet 

Chloride  of  sodium 0207  .0347  .3920 

"          potassium 0496  .0076  .0318 

Sulphate  of  potash 0081  

Carbonate  of  soda 1340  .1952  1.1353 

«           lime 1740  .0710  undet. 

"           magnesia 1287  .0278  " 

Iron-oxide,  alumina,  and  phosphates      .        traces 

Silica 0161  .0110  " 

In  1,000  parts  .      .         .         .         .         .         .5311         .3473         1.5591 

To  the  above  may  be  joined,  for  comparison,  the  analysis 
of  the  waters  of  a  large  river,  the  Ottawa,  which  drains  a 
region  occupied  chiefly  by  crystalline  rocks,  covered  by  ex- 
tensive forests  and  marshes.  The  soluble  matters  which  it 
contains  are  therefore  derived  in  part  from  the  superficial  de- 
composition of  these  rocks,  and  in  part  from  the  decaying 
vegetation.  The  water,  which  was  taken  at  the  head  of  the 
St.  Anne's  rapids,  on  the  9th»of  March,  1854,  before  the  melt- 
ing of  the  winter's  snows  had  begun,  had  a  pale  amber-yellow 
hue,  from  dissolved  organic  matter,  which  gave  a  dark  brown 
color  to  the  residue  after  evaporation.  The  weight  of  this 
residue  from  10,000  parts,  dried  at  300°  F.,  was  .6975,  which 
after  ignition  was  reduced  to  .5340  parts.  As  seen  in  the 
table  below,  one  half  of  the  solid  matters  in  this  water  were 
earthy  carbonates,  and  more  than  one  third  was  silica,  so  that 
the  whole  amount  of  salts  of  alkaline  bases  was  .088  (ofvwhich 
nearly  one  half  is  carbonate  of  soda) ;  while  the  St.  Ours  water, 
which  resembles  that  of  the  Ottawa  in  its  alkaline  salts,  con- 
tains in  the  same  quantity  4.248,  or  more  than  forty-eight 
times  as  much.  The  alkalies  of  the  Ottawa  water  equalled 
as  chlorides  .0900,  of  which  .0293,  or  32.5  per  cent,  were 
chloride  of  potassium.  The  results  of  some,  observations  on 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  127 

the  silica  and  the  organic  matters  of  this  river-water  will  be 
given  further  on  (§§  70,  71).  It  will  be  observed  that  while 
the  contents  of  all  the  other  waters  in  this  paper  are  given  for 
1,000  parts,  those  of  the  Ottawa  are  calculated  for  10,000  parts. 

Water  of  the  Ottawa  River. 

Chloride  of  potassium  t 0169 

Sulphate  of  soda 0188 

'*          potassium 0122 

Carbonate  of  soda 0410 

"  lime 2680 

"  magnesia 0690 

Iron-oxide,  alumina,  and  phosphates traces 

Silica 2060 

In  10,000  pails 6116 

§  47.  It  was  an  interesting  question  to  determine  whether  the 
composition  of  these  various  waters  remains  constant.  Having 
collected  and  analyzed,  in  September,  1847,  the  waters  of  three 
springs  in  Caledonia,  Ontario,  belonging  to  Class  III.,  and  not 
far  from  the  spring  of  Class  II.  in  the  same  town,  noticed  in 
§  42,  I  again  visited  and  collected  for  examination  the  waters 
of  the  same  springs  in  January,  1865,  after  a  lapse  of  more 
than  seventeen  years.  The  results,  when  compared  as  below, 
show  that  considerable  changes  have  occurred  in  the  compo- 
sition of  each  of  these  springs,  and  tend  to  confirm  in  an 
unexpected  manner  the  theory  which  I  had  long  before  put 
forward,  —  that  the  waters  of  the  second  and  third  classes 
owe  their  origin  to  the  mingling  of  saline  waters  of  the  first 
class  with  alkaline  waters  of  the  fourth  class.  It  will  be 
observed  that  the  three  Caledonia  waters  in  1847  were  all 
alkaline,  although  the  proportions  of  carbonate  of  soda  were 
unlike.  Sulphates  were  then  present  in  all  of  them,  but  most 
abundant  in  the  Sulphur  Spring,  which,  although  holding  the 
smallest  amount  of  solid  matters,  was  the  most  alkaline.  In 
January,  1865,  however,  the  first  and  second  of  these  waters 
had  ceased  to  be  alkaline,  and  contained,  instead  of  carbonate 
of  soda,  small  quantities  of  earthy  chloride,  causing  them  to 
enter  into  the  second  class.  They  no  longer  contained  any 


128  CHEMISTRY  OF  NATURAL   WATERS.  [IX. 

sulphates,  but,  on  the  contrary,  portions  of  baryta  and  strontia. 
Only  the  Sulphur  Spring,  which  in  1847  contained  the  largest 
proportion  of  carbonate  of  soda  and  of  sulphates,  still  retained 
these  elements,  though  in  diminished  amounts,  and  was  feebly 
impregnated  with  sulphuretted  hydrogen.  If  we  suppose  these 
waters  to  arise  from  the  commingling  of  saline  waters  of  the 
first  or  second  class,  like  those  of  Whitby  and  Lanoraie,  con- 
taining earthy  chlorides  and  salts  of  baryta  and  strontia,  with 
a  water  of  the  fourth  class  holding  carbonate  and  sulphate  of 
soda,  it  is  evident  that  a  sufficient  quantity  of  the  latter  water 
would  decompose  ,the  earthy  chlorides  and  precipitate  the  salts 
of  baryta  and  strontia  present,  while  an  excess  would  give  use 
to  alkaline-saline  waters  containing  sulphate  and  carbonate  of 
soda,  such  as  were  the  three  springs  of  Caledonia  in  1847. 
A  falling  off  in  the  supply  of  the  sulphated  alkaline  water 
may  be  supposed  to  have  taken  place,  and  the  result  is  seen 
in  the  appearance  of  chloride  of  magnesium  and  of  baryta  and 
strontia  in  two  of  the  springs,  and  in  a  diminished  proportion 
of  carbonate  of  soda  in  the  Sulphur  Spring.* 

These  later  analyses  being  directed  chiefly  to  the  determina- 
tion of  these  changes,  no  attempt  was  made  to  determine  potas- 
sium, iodine,  or  bromine.  For  the  purposes  of  comparison, 
the  two  series  of  analyses t  are  here  put  in  juxtaposition;  the 
element  just  mentioned  being  included  with  the  chloride  of 
sodium,  and  the  figures  reduced  to  three  places  of  decimals. 
The  precipitate  by  a  solution  of  gypsum  from  the  concentrated 
and  acidulated  water  was  regarded  as  sulphate  of  strontia,  and 
calculated  as  such,  but  was  in  part  sulphate  of  baryta. 

*  [The  Harrowgate  springs,  in  England,  have  undergone  changes  not  un- 
like those  of  Caledonia.  Several  of  the  Harrowgate  waters,  all  of  which  were 
found  by  Dr.  Hofnian,  in  1854,  to  contain  sulphate  of  lime,  were  examined  by 
Mr.  Davis,  in  1866,  and  found,  with  one  exception,  to  be  free  from  sulphate, 
and  to  contain  instead  salts  of  baryta,  even  in  the  sulphuretted  waters.  Great 
differences  are  there,  as  elsewhere,  observed  between  closely  adjacent  springs; 
and  in  one  of  them,  a  strong  saline  holding  chloride  of  barium,  Dr.  Muspratt 
detected  a  small  amount  of  protochloride  of  iron.  (Chemical  News,  Vol  XIII., 
passim.)] 

t  [The  complete  earlier  analyses  are  given  in  the  original  paper.] 


DL] 


CHEMISTRY  OF  NATURAL  WATERS. 


129 


Table  showing  the  Changes  in  the  Caledonia  Springs. 


Chlor.  sodium     . 
"     magnesium  . 
Sulph.  potash 
Garb,  soda 
"     lime 
"     magnesia 
"      strontia     . 
Silica     . 

In  1,000  parts    . 

1.  Gas  Spring. 

2.  Saline  Spring. 

3.  Sulphur  Spring. 

1847. 

1866. 

1847. 

1865. 

1847. 

1865. 

7.014 

.005 
.048 
.148 
.526 

6.570 
.024 

6.488 

.005 
.176 
.117 
.517 

.042 

6.930 
.026 

.095 
.469 
.012 
.015 

3.876 

3.685 

.018 
.456 
.210 
.294 

.084 

.021 
.091 
.077 
.228 

.021 

.096 
.455 
.009 
.020 

.021 

7.772 

7.174 

7.345 

7.547 

4.938 

4.123 

In  the  later  analyses  of  these  waters,  the  carbonic  acid  in  the 
Gas  Spring  was  found  to  equal,  for  1,000  parts,  .671 ;  of  which 
.278  were  required  for  the  neutral  carbonates.  The  Saline 
Spring  contained  .664  of  carbonic  acid ;  of  which  .290  go  to 
make  up  the  neutral  carbonates.  The  Sulphur  Spring,  in  like 
manner,  gave  of  carbonic  acid  .573 ;  while  the  neutral  carbon- 
ates of  the  water  require  only  .191.  All  of  these  waters,  in 
January,  1865,  thus  contained  an  excess  of  carbonic  acid  above 
that  required  to  form  bicarbonates  with  the  carbonated  bases  pres- 
ent;  while  the  analyses  of  the  same  springs  in  1847  showed 
a  quantity  of  carbonic  acid  insufficient  for  the  formation  of  bi- 
carbonates with  these  bases.  The  questions  of  the  cause  of 
this  deficiency,  and  of  the  variation  in  the  amount  of  carbonic 
acid  in  these  and  other  waters,  will  be  considered  in  the  third 
part  of  this  paper. 

§  48.  The  waters  of  our  fifth  and  sixth  classes,  as  defined  in 
§  34,  are  distinguished  by  the  presence  of  sulphates ;  the  for- 
mer being  acid,  and  the  latter  being  neutral  waters.  In  the 
fifth  class  the  principal  element  is  sulphuric  acid,  associated 
with  variable  and  accidental  amounts  of  sulphates  of  alkalies, 
lime,  magnesia,  alumina,  and  iron.  Apart  from  the  springs  of 
6*  i 


130  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

this  kind  which  occur  in  regions  where  volcanic  agencies  are 
evidently  active,  the  only  ones  hitherto  studied  are  those  of 
New  York  and  western  Canada,  which  issue  from  almost 
horizontal  Silurian  rocks  (§  31).  The  first  account  of  these 
remarkable  waters  was  given  in  the  Amer.  Jour.  Sci.  in  1829 
(Vol.  XV.  p.  238),  by  the  late  Professor  Eaton,  who  described 
two  acid  springs  in  Byron,  Genesee  County,  N.  Y.  ;  one  yield- 
ing a  stream  of  distinctly  acid  water  sufficient  to  turn  a  mill- 
wheel,  and  the  other  affording  in  smaller  quantities  a  much 
more  acid  water.  The  latter  was  afterwards  examined  by  Dr. 
Lewis  Beck  (Mineralogy  of  New  York,  p.  150).  He  found  it 
to  be  colorless,  transparent,  and  intensely  acid,  with  a  specific 
gravity  of  1.113;  which  corresponds  to  a  solution  holding 
seventeen  per  cent  of  oil  of  vitriol.  No  chlorides,  and  only 
traces  of  lime  and  iron,  were  found  in  this  water,  which  was 
nearly  pure  dilute  sulphuric  acid.  Professor  Hall  (Geology  of 
New  York,  4th  District,  p.  1 34)  has  noticed,  in  addition  to 
these,  several  other  springs  and  wells  of  acid  water  in  the 
adjacent  town  of  Bergen.  Farther  westward,  in  the  town  of 
Alabama,  is  a  similar  water,  whose  analysis  by  Erni  and  Craw 
will  be  found  in  the  Amer.  Jour.  Sci.  (2),  IX.  450.  It  con- 
tained in  1,000  parts  about  2.5  of  sulphuric  acid,  and  4.6  parts 
of  sulphates,  chiefly  of  lime,  magnesia,  iron,  and  alumina.  In 
this,  as  in  the  succeeding  analyses,  hydrated  sulphuric  acid, 
SO3,HO,  is  meant. 

The  earliest  quantitative  analyses  of  any  of  these  waters 
were  those  by  Croft  and  myself  of  a  spring  at  Tuscarora,  in 
1845  and  1847,  of  which  the  detailed  results  appear  in  the 
Amer.  Jour.  Sci.  (2),  VIII.  364.  This,  at  the  time  of  my 
analysis  in  September,  1847,  contained,  in  1,000  parts,  4.29  of 
sulphuric  acid,  and  only  1.87  of  sulphates  ;  while  the  previous 
analysis  by  Professor  Croft  gave  approximatively  3.00  of  neutral 
sulphates,  and  only  about  1.37  of  sulphuric  acid.  Similar 
acid  waters  occur  on  Grand  Island  above  Niagara  Falls  and  at 
Chippewa. 

All  of  these  springs,  along  a  line  of  more  than  100  miles 
from  east  to  west,  rise  from  the  outcrop  of  the  Onondaga  salt- 


IX.]         CHEMISTRY  OF  NATURAL  WATERS.        131 

group ;  but  in  the  township  of  Niagara,  not  far  from  Queenston, 
are  two  similar  waters  which  issue  from  the  Medina  sandstone. 
One  of  these  is  in  the  southwest  part  of  the  township,  and  fills 
a  small  basin  in  yellow  clay,  which,  at  a  depth  of  three  or  four 
feet,  is  underlaid  by  red  and  green  sandstones.  The  water, 
which,  like  those  of  Tuscarora  and  Chippewa,  is  slightly  im- 
pregnated with  sulphuretted  hydrogen,  is  kept  in  constant 
agitation  from  the  escape  of  inflammable  gas.  It  contained  in 
1,000  parts  about  two  parts  of  free  sulphuric  acid,  and  less  than 
one  part  of  neutral  sulphates.  This  water  was  collected  in 
October,  1849,  and  at  that  time  another  half-dried-up  pool  in 
the  vicinity  contained  a  still  more  acid  water.  Another  similar 
spring  occurs  near  St.  David,  in  the  same  township.  In  con- 
nection with  the  suggestion  made  in  §  31  as  to  their  probable 
origin  at  great  depths,  it  would  be  very  desirable  to  have 
careful  observations  as  to  the  temperature  of  these  acid  springs. 
When,  oil  the  19th  October,  1847,  I  visited  the  Tuscarora 
spring,  the  water  in  two  of  the  small  pools  had  a  temperature 
of  56°  F. ;  but  on  plunging  the  thermometer  in  the  mud  at 
the  bottom  of  one  of  these  it  rose  to  60.5°. 

§  49.  It  appears  from  a  comparison  of  the  analysis  of  Croft 
with  my  own  that  the  waters  of  the  Tuscarora  spring  under- 
went a  considerable  change  in  composition  in  the  space  of  two 
years ;  the  proportion  of  the  bases  to  the  acid  at  the  time  of 
the  second  analysis  being  little  more  than  one  third  of  that  in 
the  analysis  of  Croft.  This  change  was  indeed  to  be  expected, 
since  waters  of  this  kind  must  soon  remove  the  soluble  constit- 
uents from  the  rocks  through  which  they  flow,  and  eventually 
become,  like  the  water  from  Byron,  little  more  than  a  solution 
of  sulphuric  acid.  The  observations  of  Eaton  at  Byron,  and 
my.  own  at  Tuscarora,  show  that  half-decayed  trees  are  still 
standing  on  the  soil  which  is  now  so  impregnated  with  acid 
waters  as  to  be  unfit  to  support  vegetation.  Reasoning  from 
the  changes  in  composition,  it  may  be  supposed  that  these 
waters  were  at  first  neutral,  the  whole  of  the  acid  being  satu- 
rated by  the  calcareous  rocks  through  wtych  they  must  rise.  It 
was  from  this  consideration  that  I  was  formerly  led  to  ascribe 


132  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

to  the  action  of  these  waters  the  formation  of  some  of  the 
masses  of  gypsum  which  appear  along  the  outcrop  of  the  Onon- 
daga  salt-group  (Anier.  Jour.  Sci.  (2),  VII.  175).  That  waters 
like  those  just  mentioned  must  give  rise  to  sulphate  of  lime  by 
their  action  on  calcareous  rocks  is  evident ;  and  some  of  the 
deposits  of  gypsum  in  this  region,  as  described  by  good  observ- 
ers, would  appear  to  be  thus  formed.  So  far,  however,  as  my 
personal  observations  of  the  gypsums  of  western  Canada  have 
extended,  these  appear  to  be  in  all  cases  contemporaneous  with 
the  shales  and  dolomites  with  which  they  are  interstratified, 
and  to  have  no  connection  with  the  sulphuric-acid  springs 
which  are  so  common  throughout  that  region.  (Ibid.  (2), 
XXVIII.  365  ;  and  Geology  of  Canada,  352.) 

§  50.  We  have  included  in  a  sixth  class  the  various  neutral 
saline  waters  in  which  sulphates  predominate,  sometimes  to 
the  exclusion  of  chlorides.  The  bases  of  these  waters  are 
soda,  potash,  lime,  and  magnesia ;  which  are  usually  found 
together,  though  in  varying  proportions.  For  the  better  under- 
standing of  the  relations  of  these  sulphated  waters,  it  may  be 
well  to  recapitulate  what  has  been  said  about  their  origin ; 
and  to  consider  them,  from  this  point  of  view,  under  two 
heads. 

First,  those  formed  from  the  solution  of  neutral  sulphates 
previously  existing  in  a  solid  form  in  the  earth.  Strata  en- 
closing natural  deposits  of  sulphates  of  soda  and  magnesia, 
sometimes  with  sulphate  of  potash  (§§  17,  19),  afford  the 
most  obvious  source  of  these  waters.  The  frequent  occurrence 
of  gypsum,  however,  points  to  this  salt  as  a  more  abundant 
source  of  sulphated  waters.  Solutions  of  gypsum  may  in  some 
case  exchange  their  lime  for  the  soda  of  insoluble  silicates,  or 
this  salt  may  be  decomposed  by  solutions  of  carbonate  of  soda 
(§§  7,  19).  The  decomposition  of  the  sulphate  of  lime  by 
hydrous  carbonate  of  magnesia,  as  explained  in  §  21,  is  doubt- 
less in  many  cases  the  source  of  sulphate  of  magnesia,  which, 
more  frequently  than  sulphate  of  soda,  is  a  predominant  element 
in  mineral  waters.  In  connection  with  a  suggestion  made  in 
the  section  last  cited,  it  may  be  remarked  that  I  have  since 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  133 

found  that  predazzite,  in  virtue  of  the  hydrate  of  magnesia 
which  it  contains,  readily  decomposes  solutions  of  gypsum 
holding  dissolved  carbonic  acid,  and  gives  rise  to  sulphate 
of  magnesia. 

In  the  second  place,  sulphuric-acid  waters,  like  those  de- 
scribed in  §  47,  by  their  action  upon  calcareous  and  magne- 
sian  rocks,  or  by  the  intervention  of  carbonate  of  soda,  may,  as 
already  suggested,  give  rise  to  neutral  sulphated  waters  of  the 
sixth  class.  It  is  evident  also  that  w.aters  impregnated  with 
sulphates  of  alumina  and  iron  from  oxidizing  sulphates,  as 
mentioned  in  §  28,  may  be  decomposed  in  a  similar  manner, 
and  with  like  results. 

Neutral  sulphated  waters  generated  by  any  of  the  above 
processes  are  evidently  subject  to  admixtures  of  saline  matters 
from  other  sources,  and  may  thus  become  impregnated  with 
chlorides  and  carbonates.  Indeed,  it  is  rare  to  find  waters  of 
the  sixth  class  without  some  portion  of  chlorides  ;  and  a  tran- 
sition is  thus  presented  to  the  waters  of  the  first  four  classes, 
in  which  also  portions  of  sulphates  are  of  frequent  occurrence. 
The  presence  of  sulphates  being  one  of  the  conditions  required 
for  the  generation  of  sulphuretted  hydrogen  (§  10),  we  find 
that  the  waters  of  the  sixth  class  are  very  often  sulphurous. 

§  51.  Waters  of  the  sixth  class  are  very  frequently  met  with 
in  the  palaeozoic  rocks  of  New  York  and  western  Canada,  and 
are  probably  derived  from  the  gypsum  which  is  found  in  great- 
er or  less  abundance  at  various  horizons,  from  the  Calciferous 
sand-rock  to  the  Ouondaga  salt-group.  It  is,  however,  not 
improbable  that  the  sulphuric-acid  waters  which  abound  in  this 
region  (§  48)  may,  by  their  neutralization,  give  rise  to  similar 
springs.  In  the  waters  of  the  district  under  consideration,  the 
sulphate  of  lime  generally  predominates  over  the  sulphates  of 
the  other  bases,  and  chlorides  are  frequently  present  in  consid- 
erable quantities.  For  numerous  analyses  of  these  waters,  see 
Beck,  Mineralogy  of  New  York.  The  results  of  an  examina- 
tion by  me  of  the  Charlotteville  spring,  remarkable  for  the 
amount  of  sulphuretted  hydrogen  which  it  contains,  will  be 
found  in  the  Amer.  Jour.  Sci.  (2),  VIII.  369.  A  copious  sul- 


134  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

phur  spring  which  issues  from  a  mound  of  calcareous  tufa  in 
Brant,  in  Ontario,  overlying  the  Corniferous  limestone,  is  dis- 
tinguished by  the  absence  of  any  trace  of  chlorides  \  in  which 
respect  it  resembles  the  acid  waters  of  the  fifth  class  from  the 
adjacent  region.  A  partial  analysis  of  a  portion  of  it  collected 
in  1861  gave,  for  1,000  parts,  sulphate  of  lime  1.240,  sulphate 
of  magnesia  .207,  and  carbonate  of  lime  .198.  From  a  slight 
excess  in  the  amount  of  sulphuric  acid,  it  is  probable  that  a 
little  sulphate  of  soda  was  also  present. 

Of  waters  of  this  class,  in  which  sulphate  of  magnesia  pre- 
dominates, but  few  have  yet  been  observed  in  this  country. 
A  remarkable  example  of  this  kind,  from  Hamilton,  Ontario, 
was  examined  by  Professor  Croft,  of  Toronto,  and  described 
by  him  in  the  Canadian  Journal  for  1853  (page  153).  It 
had  a  specific  gravity  of  1006,4,  and  gave,  for  1,000  parts,  — 

Chloride  of  sodium 5098 

Sulphate  of  soda 1.6985 

"  lime 1.1246 

"  magnesia 4.7799 

8.1128 

The  rocks  exposed  at  Hamilton  include  the  Medina  sand- 
stone and  the  Niagara  limestone,  with  the  intermediate  Clin- 
ton group.  Along  the  outcrop  of  the  latter,  crystalline  crusts 
of  nearly  pure  sulphate  of  magnesia  are  observed  to  form  in 
many  localities,  during  the  dry  season  of  the  year.  (Geology 
of  Canada,  460.) 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  135 

ILL 

CHEMICAL  AND  GEOLOGICAL  CONSIDERATIONS. 

CONTENTS  OF  SECTIONS.  — 52.  Salts  of  alkaline  metals;  proportion  and  sources 
of  potash  ;  53.  Potassium  and  sodium  in  the  primitive  sea  ;  54.  Salts  of 
lime  and  magnesia;  relations  of  chlorides  and  carbonates ;  55.  Solubility 
of  earthy  carbonates  ;  56.  Supersaturated  solutions  of  carbonates  of  lime 
and  magnesia  ;  57.  Salts  of  barium  and  strontium ;  solution  of  their  sul- 
phates ;  58.  Iron,  manganese,  alumina,  and  phosphates ;  59.  Bromides 
and  iodides  ;  the  small  portion  of  bromine  and  the  excess  of  iodine  in 
saline  springs  as  compared  with  the  modern  ocean;  60.  Probable  relation 
of  iodides  to  sediments;  61.  Sulphates,  their  elimination  from  waters; 
62.  Water  holding  a  soluble  sulphuret ;  63.  Borates,  their  detection  ; 
64.  Analysis  of  a  borax-water  from  California  ;  65.  Carbonates,  their 
amount  in  the  Caledonia  waters ;  66.  Intervention  of  neutral  carbonate 
of  soda  ;  67.  Deficiency  of  carbonic  acid  in  waters  ;  68.  Reactions  of  vari- 
ous waters;  69.  Silica,  its  source  and  its  proportion;  70.  Its  conditions ; 
formation  of  silicates  ;  71.  Organic  matters  ;  72.  Geological  position  of 
the  waters  here  described  ;  73.  Succession  of  palaeozoic  strata  ;  litlio- 
logical  relations  of  successive  formations  ;  74.  Quebec  group,  its  waters  ; 
75.  Sources  of  various  classes  of  waters  ;  76.  Their  relation  to  the  forma- 
tions ;  77.  Associations  of  unlike  waters  ;  changes  in  constitution  ;  78. 
Temperature  of  springs  ;  thermal  waters  ;  79.  Geological  interest  of  the 
above  analyses  ;  possible  results  of  the  evaporation  of  these  springs. 

§  52.  SALTS  OF  THE  ALKALINE  METALS. — These  salts  abound 
in  most  saline  waters,  and,  except  in  the  few  cases  in  which 
sulphate  of  magnesia  prevails,  form  a  large  part  of  the  soluble 
matters  present.  The  salts  of  sodium  are  by  far  the  most  abun- 
dant, and  the  proportion  of  potassium-salt  is  generally  small. 
The  chloride  of  potassium  in  modern  sea-water  constitutes  three 
or  four  hundredths  of  the  alkaline  chlorides,  while  in  the  brines 
from  old  rocks,  and  in  saline  waters  of  the  first  two  classes 
alike  from  Germany,  England,  the  United  States,  and  Canada, 
its  proportion  is  much  less,  sometimes  amounting  to  traces  only. 
In  the  waters  of  Classes  III.  and  IV.,  where  alkaline  carbon- 
,ates  appear,  and  even  predominate,  the  proportion  of  potassium- 
salt  becomes  greater.  Thus  of  the  waters  of  the  latter  class 
(§  45),  the  alkalies  of  the  Nicolet  spring  calculated  as  chlorides 
contain  1.89  per  cent  of  chloride  of  potassium,  and  those  of 
the  Jacques-Cartier  2.95;  while  for  the  St.  Ours  spring  the 


136  CHEMISTKY  OF  NATURAL  WATERS.  [IX. 

chloride  of  potassium  is  equal  to  not  less  than  25.0  per  cent. 
There  does  not,  however,  appear  to  be  any  relation  between 
the  proportion  of  alkaline  carbonate  and  that  of  potassium, 
since  the  salts  from  the  waters  first  named  are  more  alkaline 
than  those  of  St.  Ours ;  while  those  of  the  alkaline  water  of 
Joly  contain  less  than  one  per  cent  of  potassic  chloride. 

The  amount  of  this  salt  obtained  from  the  water  of  the 
Ottawa  Eiver  is  worthy  of  notice,  being  equal  to  not  less  than 
32.0  per  cent  of  the  alkaline  chlorides,  while  in  the  waters  of 
the  St.  Lawrence  it  amounts  to  16.0  per  cent.*  A  large  pro- 
portion of  potassium  relatively  to  the  sodium  has  already  been* 
observed  in  the  case  of  many  ordinary  river  and  spring  waters, 
and  this  is  readily  explained  when  we  consider  the  extent  to 
which  potash  is  set  free  by  the  decomposition  of  both  vegetal 
and  mineral  matters  at  the  earth's  surface.  The  process  by 
which  this  base  is  eliminated  in  filtering  through  soils  has 
already  been  explained  in  §  5.  The  occasional  presence  of 
considerable  amounts  of  potash  in  sulphated  mineral  waters 
(Lersch,  Hydro-chemie,  page  346)  is  explained  by  the  power 
of  solutions  of  gypsum  to  set  free  this  alkali  from  soils  (§7), 
and  also  probably  in  some  cases  by  the  dissolution  of  double 
potassic  salts  like  polyhallite.  Strata  holding  glauconite,  which 
occurs  alike  in  paleozoic  and  more  recent  formations,  t  may  also 
be  conceived  to  yield  potash-salts  to  infiltrating  waters. 

§  53.  It  will  be  seen  that  the  waters  above  noticed,  in 
which  the  proportion  of  the  potash  to  the  soda  is  large,  are 
but  feebly  saline,  so  that  the  real  amount  of  potassium  is  in 
no  case  great.  The  fact  of  especial  importance  as  regards 
the  alkaline  metals  in  the  waters  whose  analyses  we  have  given 


*  See  London,  Edinburgh  and  Dublin  Phil.  Mag.  (4),  XIII.  239,  and  Geol- 
ogy of  Canada,  page  565,  where  analyses  of  both  of  these  waters  may  be 
found. 

-(•  For  a  notice,  with  analyses  by  the  author,  of  a  green  hydrated  silicate 
of  alumina,  iron  and  potash,  allied  to  glauconite,  from  the  palaeozoic  rocks 
of  Canada  and  of  the  Mississippi  valley,  see  the  Geology  of  Canada,  pages 
487,  488;  where  also  will  be  found  an  analysis  by  the  author  of  the  glauconite 
from  the  cretaceous  formation  of  New  Jersey.  See  also  Amer.  Jour.  Science 
(2),  XXX.  277. 


IX.]         CHEMISTRY  OF  NATURAL  WATERS.        137 

in  this  paper  is  the  very  small  amount  of  potassium  in  the 
strongly  saline  muriated  waters  of  the  first  three  classes,  which 
we  conceive  to  be  more  or  less  directly  derived  from  the  waters 
of  the  ancient  ocean.  To  this  primeval  sea,  almost  destitute 
of  potassium,  the  process  of  mineral  decay  has  been  for  ages 
adding  potash-salts,  and,  despite  the  partial  elimination  of 
these  by  vegetation  (§  5),  and  by  the  formation  of  glauconite, 
we  find  a  notable  proportion  of  potash  in  the  waters  of  the 
modern  ocean. 

In  the  analyses  of  the  saline  waters  here  given  lithia  was 
sought  for  in  a  few  instances,  and  was  detected  in  the  waters 
of  Varennes.  Most  of  these  analyses  were  made  before  the 
discovery  of  the  new  metals  caesium  and  rubidium. 

§  54.  SALTS  OF  CALCIUM  AND  MAGNESIUM.  —  We  have  to 
consider  under  this  head  the  relations  both  of  the  chlorides 
and  the  carbonates  of  these  bases.  The  bitter  saline  waters 
of  the  first  class,  although  containing  large  quantities  of  chlo- 
rides of  calcium  and  magnesium,  are,  as  we  have  seen,  gener- 
ally destitute  of  earthy  carbonates.  These  latter,  however,  are 
found  in  small  quantities  in  the  alkaline  waters  of  the  fourth 
class,  and  in  somewhat  larger  amounts  in  those  intermediate 
waters  which  form  Classes  II.  and  III.,  and  are  apparently 
formed  by  admixtures  of  the  two  classes  previously  mentioned. 
Besides  the  carbonates  of  lime  and  magnesia  which  the  waters 
of  the  fourth  class  hold  in  solution,  the  carbonate  of  soda 
which  they  contain  gives  rise,  by  its  reaction  with  the  chlo- 
rides of  calcium  and  magnesium,  to  additional  quantities  of 
the  carbonates  of  these  bases.  In  the  bitter  saline  waters  of 
Kingston  (described  in  the  original  paper)  a  large  amount 
of  chloride  of  calcium  is  associated  with  earthy  carbonates, 
and  these  waters  thus  offer  a  passage  from  the  first  to  the  sec- 
ond class. 

.  In  most  of  the  waters  of  the  second  class,  as  will  be  seen 
from  the  table  in  §  42,  there  appears  but  a  small  amount  of 
chloride  of  calcium ;  and  even  this  depends  upon  the  manner 
in  which  the  analysis  has  been  conducted.  We  may  suppose 
in  the  recent  water  such  a  partition  of  bases  between  the  chlo- 


138  CHEMISTRY  OF   NATURAL  WATERS.  [IX. 

rine  and  the  carbonic  acid  that  chloride  of  calcium,  chloride  of 
magnesium,  bicarbonate  of  lime,  and  bicarbonate  of  magnesia 
coexist.  When  such  a  solution  is  submitted  to  evaporation 
at  ordinary  temperatures,  provided  there  is  present  a  sufficient 
amount  of  chloride  of  calcium,  carbonate  of  lime  alone  is  de- 
posited, and  chloride  of  magnesium  remains  in  solution.  In 
case  the  chloride  of  calcium  is  insufficient,  the  lime  is  still  first 
deposited  as  carbonate,  and  the  more  soluble  magnesian  car- 
bonate is  precipitated  by  further  evaporation.  When,  how- 
ever, such  a  water  is  boiled,  a  reverse  process  takes  place,  — 
the  carbonate  of  lime  slowly  decomposes  tfie  magnesian  chlo- 
ride, and  carbonate  of  magnesia  is  deposited,  while  chloride 
of  calcium  remains  in  solution.  Hence  if  the  amount  of  chlo- 
ride of  magnesium  be  great  enough,  and  the  ebullition  suffi- 
ciently prolonged,  the  precipitate  will  at  length  contain  only 
carbonate  of  magnesia ;  while  an  equivalent  of  chloride  of  cal- 
cium, now  found  in  the  solution,  represents  the  carbonate  of 
lime  which  the  analysis  of  the  precipitate  at  an  earlier  stage 
of  the  ebullition  would  have  furnished. 

As  an  example  of  this  may  be  cited  the  analysis  of  a  water 
of  Class  II.  from  Ste.  Genevieve,  where  the  precipitate,  after 
a  few  minutes'  boiling,  contained  carbonates  of  lime  and  mag- 
nesia in  the  proportion  12  :  750.  When,  however,  another 
portion  was  boiled  down  to  one  sixth,  the  precipitate  was 
found  to  be  pure  carbonate  of  magnesia.  The  water  of  another 
spring  of  the  same  class,  that  of  Plantagenet,  [described  in  the 
original  paper,]  gave  as  the  result  of  ebullition  a  precipitate 
of  .8904  of  carbonate  of  magnesia  and  .0330  of  carbonate  of 
lime  ;  while  the  liquid  retained  a  portion  of  lime  equal  to  .1364 
of  chloride  of  calcium,  besides  .2452  of  chloride  of  magnesium, 
in  1,000  parts.  When,  however,  this  water  is  left  to  spon- 
taneous evaporation,  the  whole  of  the  lime  separates  as  carbon- 
ate, and  the  liquid  remains  for  a  time  charged  with  carbonate 
of  magnesia,  probably  as  sesqui-carbonate.  This  solution  is, 
however,  after  a  time  spontaneously  decomposed  even  in  closed 
vessels,  with  deposition  of  a  portion  of  crystalline  hydrated 
carbonate  of  magnesia ;  another  portion  remains  in  solution, 


IX.]        CHEMISTRY  OF  NATURAL  WATERS.        139 

together  with  chloride  of  magnesium,  but  is  precipitated  by 
ebullition.  (Amer.  Jour.  Science  (2),  XXVII.  173.) 

§  55.  Bicarbonate  of  magnesia  and  chloride  of  calcium,  when 
brought  together  in  solution,  undergo  mutual  decomposition 
with  separation  of  carbonate  of  lime,  if  the  solutions  are  not 
too  dilute.  At  the  ordinary  temperature  and  pressure,  water 
saturated  with  carbonic  acid  will  not  hold  more  than  about  one 
gramme  of  carbonate  of  lime  to  the  litre  (1  :  1,000),  equal  to 
only  0.88  grammes  of  carbonate  of  magnesia.  (The  solubility 
of  carbonate  of  lime  in  pure  water  is  well  known  to  be  much  less, 
and  is,  according  to  Bineau,  equal  to  1  :  30,000  or  1  :  50,000.) 
We  should  not,  therefore,  expect  to  find  that  water  holding 
cliloride  of  calcium  in  solution  would  yield,  by  boiling,  more 
than  the  latter  amount  of  magnesian  carbonate ;  so  much  might 
evidently  be  formed  by  the  action  of  dissolved  carbonate  of 
lime  which  the  water  might  hold  as  bicarbonate.  I  have  else- 
where described  a  series  of  experiments  on  the  solubility  of 
bicarbonate  of  lime  both  in  pure  water  and  in  saline  solutions, 
and  have  shown  that  the  presence  of  salts  of  soda,  lime,  and 
magnesia  does  not  increase  the  amount  of  bicarbonate  of  lime 

which  water  is  capable  of  holding  permanently  in  solution 

Recent  experiments  have,  however,  shown  me  that  supersatu- 
rated solutions  of  a  certain  stability  may  be  obtained,  in  which 
comparatively  large  quantities  of  neutral  carbonates  of  lime 
and  magnesia  exist  in  the  presence  of  sulphates  and  chlorides 
of  calcium  and  magnesium. 

§  56.  In  a  memoir  on  the  salts  of  lime  and  magnesia  pub- 
lished in  1859  (Amer.  Jour.  Science  (2),  XXVIII.  171),  it. 
was  shown  that  by  the  addition  of  bicarbonate  of  soda  to  a 
solution  holding  chlorides  of  sodium,  calcium  and  magnesium, 
with  or  without  sulphate  of  soda,  and  saturated  with  carbonic 
acid,  it  is  possible  to  obtain  transparent  solutions  holding  from 
3.40  to  4.16  grammes  of  carbonate  of  lime  to  the  litre.  Of 
this,  however,  the  greater  part  was  deposited  after  twenty- 
four  hours,  when  the  solutions  were  found  to  contain  some- 
what less  than  1.0  gramme,  in  the  form  of  bicarbonate.  Bou- 
tron  and  Boudet  had  previously  shown  that  by  saturating  lime- 


140  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

water  with  carbonic  acid,  solutions  were  obtained  holding  in  a 
litre  2.3  grammes  of  carbonate  of  lime ;  of  which  one  half  was 
soon  deposited,  even  when  the  solution  was  kept  under  a 
pressure  of  several  atmospheres.  It  would  thus  seem  that 
saline  liquids  favor  this  temporary  solubility"  of  the  carbonate 
of  lime  as  bicarbonates. 

In  all  of  the  above  experiments  an  excess  of  carbonic  acid 
was  present,  but  this  I  have  since  found  is  not  essential,  since 
supersaturated  solutions  may  be  obtained  holding  as  much  as 
1.2  grammes  of  carbonate  of  lime,  together  with  sulphate  of 
magnesium  and  chloride  of  calcium,  in  a  litre  of  water,  without 
any  excess  of  carbonic  acid.  The  power  of  alkaline  chlorides 
and  of  chloride  of  calcium  to  prevent  the  precipitation  of  chlo- 
ride of  calcium  by  carbonate  of  soda  has  already  been  observed 
by  Storer  (Dictionary  of  Solubilities,  page- 110).  I  have  found 
that  the  precipitate  produced  by  the  admixture  of  solutions  of 
these  two  salts  is  readily  dissolved,  when  recent,  by  a  solution 
of  chloride  of  calcium  or  of  sulphate  of  magnesia;  and  thus 
liquids  may  be  prepared  holding  at  the  same  time  from  1.0  to 
1.2  grammes  of  neutral  carbonate  of  lime  and  1.0  of  neutral  car- 
bonate of  magnesia,  in  presence  of  sulphate  of  magnesia.  These 
solutions  of  carbonate  of  lime,  which  are  strongly  alkaline,  may 
be  kept  for  twelve  hours  or  more  without  perceptible  change 
at  ordinary  temperatures,  but  after  a  time  deposit  crystals  of 
hydrated  carbonate  of  lime.  The  addition  of  alcohol  imme- 
diately throws  down  the  whole  of  the  carbonate  of  lime  in  an 
amorphous  condition. 

The  carbonate  of  magnesia  is  still  more  soluble  than  the 
carbonate  of  lime  under  similar  conditions,  and  it  is  possible  to 
obtain  5.0  grammes  of  neutral  carbonate  of  magnesia  dissolved 
in  a  litre  of  water  holding  seven  per  cent  of  hydrated  sulphate 
of  magnesia,  without  any  excess  of  carbonic  acid.  These  solu- 
tions, which  are  strongly  alkaline  to  test-papers,  yield  a  precipi- 
tate by  heat,  which  redissolves  on  cooling. 

It  is  evident  that  the  mingling  of  saline  and  alkaline  waters 
may  give  rise  to  solutions  like  those  just  described,  and  thus 
explain  apparent  anomalies  in  the  composition  of  certain  saline 


IX.]  CHEMISTRY   OF  NATURAL  WATERS.  141 

waters.  See  also  in  this  connection  the  observations  of  Bineau, 
and  my  own  on  the  properties  of  solutions  of  sesqui-carbonate 
of  magnesia.  (Amer.  Jour.  Science  (2),  XXVII.  173.) 

§57.  SALTS  OF  BARIUM  AND  STRONTIUM.  —  The  salts  of 
these  two  bases  are  found  in  very  many  of  the  saline  and 
alkaline  waters  of  Canada.  Their  carbonates  probably  sustain 
to  the  magnesian  chloride  a  similar  relation  with  that  of  cal- 
cium, and  hence  these  bases  appear  in  some  of  the  analyses 
partly  as  carbonates,  and  partly  as  chlorides  of  barium  and 
strontium.  The  precipitate  formed  in  the  concentrated  and 
acidulated  water  by  dilute  sulphuric  acid  was,  whenever  sub- 
mitted to  analysis,  found  to  contain  both  barium  and  stron- 
tium. For  the  separation  of  these,  the  mixed  sulphates  were 
first  converted  into  chlorides ;  the  barium  was  then  thrown 
down  as  silico-fluoride,  and  the  strontium  subsequently  pre- 
cipitated by  a  solution  of  gypsum. 

The  insolubility  of  its  sulphate  must  have  excluded  baryta 
from  the  waters  of  the  primeval  sea,  and  when  set  free,  as  we 
may  suppose,  by  the  decomposition  of  its  silicated  compounds 
existing  in  the  primitive  crust  (§  12),  its  soluble  bicarbonate 
carried  down  to  the  sea  would  there  be  precipitated  by  the 
sulphates  present.  A  similar  process  must  still  go  on  with 
all  the  dissolved  barytic  salts  which  find  their  way  to  the 
ocean. 

The  sulphate  of  baryta  thus  accumulated  in  sedimentary 
strata  may  be  partially  decomposed  by  infiltrating  solutions 
of  alkaline  carbonates,  and  thus  be  rendered  capable  of  being 
subsequently  dissolved  as  carbonate;  but  the  most  probable 
mode  of  its  solution  is,  we  conceive,  through  its  previous  re- 
duction by  organic  matters  to  the  form  of  a  soluble  sulphuret 
(§  10)»  ready  to  be  converted  into  carbonate  or  chloride  of 
barium.  In  this  way  we  may  explain  the  frequent  occurrence 
of  baryta-salts  in  the  saline  waters  of  the  first  three  classes, 
and  the  consequent  absence  of  sulphates,  which  will  be  further 
considered  in  §  61.  From  the  similarity  of  its  chemical  re- 
actions, the  preceding  remarks  apply  to  strontia  as  well  as 
baryta. 


142  CHEMISTKY  OF  NATURAL  WATERS.  [IX. 

§  58.  IRON,  MANGANESE,  ALUMINA,  AND  PHOSPHATES. — None 
of  the  waters  of  the  four  classes  here  described  contain  any 
notable  quantity  of  iron,  yet  this  element  is  never  wanting  in 
those  waters  which  contain  earthy  carbonates.  Whenever  a 
portion  of  one  of  these  waters,  or  better  the  earthy  precipitate 
separated  from  it  by  boiling,  is  evaporated  to  dryness  with  an 
excess  of  hydrochloric  acid,  the  residue  treated  with  acidulated 
water  yields  a  portion  of  silica,  and  the  solution  will  then  be 
found  to  yield  with  ammonia  a  precipitate.  This,  which  is 
partially  soluble  in  caustic  alkalies,  is  often  colorless,  and  will 
be  found  to  consist  of  alumina  and  peroxide  of  iron,  with  phos- 
phoric acid  and  a  trace  of  manganese,  which  latter  metal  is 
seldom  or  never  absent.  The  small  quantity  of  alumina  which 
these  waters  contain  appears  not  to  be  derived  from  suspended 
argillaceous  matters,  but  to  be  held  in  a  state  of  solution. 
The  phosphates  are  generally  present  only  in  very  small  quan- 
tities in  these  waters,  for  the  reason  pointed  out  in  §  5.  The 
largest  amount  which  I  have  met  with  was  in  an  alkaline 
water  of  Class  III.  from  Fitzroy  (§  43),  where  it  is  equal  to 
.0124  of  tribasic  phosphate  of  soda  in  1,000  parts  of  water. 

§59.  BROMIDES  AND  IODIDES.  —  The  chlorides  in  these  an- 
cient mineral  waters  are  always  accompanied  by  bromides  and 
iodides,  but  the  proportion  of  the  bromides  to  the  chlorides 
appears  to  be  much  less  than  in  the  waters  of  the  modern 
seas.  According  to  Usiglio,  100  parts  of  the  salts  from  the 
Mediterranean  contain  1.48  of  bromide  of  sodium;  while  ten 
analyses  by  Yon  Bibra  of  the  waters  of  different  oceans  give 
from  0.86  to  1.46,  affording  for  100  parts  of  salts  a  mean  of 
1.16  of  bromide  of  sodium,  equal  to  1.04  parts  of  bromide 
of  magnesium.  The  waters  of  Whitby  and  Hallowell,  on  the 
contrary,  which  are  the  richest  in  bromides  of  those  described 
in  this  paper,  contain  only  0.54  and  0.69  parts  of  bromide  of 
sodium  in  100  parts  of  solid  matters ;  while  few  of  the  saline 
springs  of  the  second  class  contain  more  than  one  half  of  this 
proportion,  and  some  of  them  very  much  less. 

With  regard  to  the  iodides  in  many  of  these  waters,  how- 
ever, the  case  is  very  different.  The  waters  of  the  modern 


IX.]        CHEMISTRY  OF  NATURAL  WATERS.        143 

ocean,  as  is  well  known,  contain  but  traces  of  iodine,*  and  in 
some  strongly  saline  springs  of  the  first  class,  like  that  of 
Whitby,  it  is  only  in  the  alcoholic  extract  of  the  salts  from 
this  water  that  iodine  can  be  detected.  The  Hallowell  water 
(§  36),  which  closely  resembles  this  in  its  general  composition, 
and  in  the  proportion  of  bromides,  is,  however,  so  rich  in 
iodine  that  its  presence  can  readily  be  discovered  without  pre- 
vious evaporation.  It  is  sufficient  to  add  to  the  recent  water 
acidulated  by  hydrochloric  acid  a  little  solution  of  starch  and 
a  few  drops  of  nitrite  of  potash,  to  produce  an  intense  blue 
color.  The  iodide  of  sodium  in  the  first-named  water  was 
found  equal  to  0.0017  parts  of  the  solid  matters,  and  that  of 
the  second  to  0.019,  or  nearly  twelve  times  as  much.  The 
unconcentrated  saline  waters  from  the  two  springs  of  Ste.  Gen- 
evieve,  which  belong  to  the  second  class,  also  give  a  strong 
reaction  for  iodine,  and  when  acidulated  with  hydrochloric 
acid,  without  previous  evaporation,  yield  with  a  salt  of  palla- 
dium a  precipitate  of  iodide  of  palladium  after  a  few  hours. 
The  salts  from  these  two  springs  of  Ste.  Genevieve,  though 
poorer  in  bromides,  are  much  richer  in  iodides,  than  the  waters 
of  Hallowell;  one  of  the  former  containing  in  100  parts  of 
salts  no  less  than  0.138  of  iodine,  so  that  there  appears  to  be 
no  constant  proportion  between  the  chlorides,  bromides  and 
iodides  of  these  saline  waters. 

§  60.  The  relations  of  bromides  and  iodides  to  argillaceous 
sediments  have  yet  to  be  determined.  It  would  appear  from 
the  facts  just  cited  that  bromine  has  in  the  course  of  ages  been 
slowly  eliminated  from  insoluble  combinations,  and,  like  potas- 
sium, has  accumulated  in  the  waters  of  the  ocean ;  while  the 
facts  in  the  history  of  iodine  seem  to  point  to  a  process  the 
reverse  of  this,  —  in  other  words,  to  a  gradual  elimination  of 
iodine  from  the  sea- waters,  and  its  fixation  in  the  earth's  crust. 
The  observations  of  numerous  chemists  unite  to  show  the  fre- 
quent occurrence  of  small  portions  of  iodine  in  some  unknown 
combination,  in  sedimentary  rocks  of  various  kinds  ;  from  which 

*  [  See  in  this  connection  the  late  researches  of  Sonstadt,  noticed  at  the 
end  of  Essay  XII.] 


144  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

we  may  conjecture  that  it  was  in  former  times  abstracted  from 
the  sea,  either  directly  or  through  the  intervention  of  organic 
bodies  (as  in  the  case  of  potash,  which  is  separated  and  fixed 
by  means  of  algae,  §  5).  Experiments  after  the  manner  of  those 
of  Way  and  Voelcker  may  throw  light  upon  this  interesting 
question.  We  are  aware  that  insoluble  combinations  of  solu- 
ble chlorides  with  silicates  of  alumina  are  found  under  certain 
conditions,  as  appears  in  sodalite,  eudialyte,  and  the  chlorifer- 
ous  micas,  and  it  is  not  improbable  that  the  soluble  iodides 
may  give  rise  to  similar  compounds.  By  such  a  process  might 
be  explained  the  rarity  of  this  element  in  modern  seas,  while 
the  occasional  re-solution  of  the  iodine  from  these  insoluble 
compounds  by  infiltrating  waters  would  help  to  explain  the 
variable  and  often  large  proportions  in  which  this  element  is 
met  with  in  some  of  the  waters  noticed  above. 

§  61.  SULPHATES.  —  In  the  preceding  sections  we  have  already 
discussed  the  principal  facts  in  the  history  of  those  neutral 
waters  in  which  sulphates  predominate,  or  prevail  to  the  ex- 
clusion of  chlorides  (§§  50,  51).  The  history  and  the  probable 
origin  of  those  curious  springs  which  contain  free  sulphuric 
acid  has  also  been  considered  ,(§§  31,  48,  49);  and  it  now  re- 
mains to  notice  the  relation  of  sulphates  to  the  muriated  waters. 
The  first  fact  that  excites  our  attention  is  that  of  the  total 
absence  of  sulphates  from  numerous  springs  of  the  first,  sec- 
ond, and  third  classes,  as  shown  in  the  preceding  analyses,  and 
also  in  the  observations  of  Lenny  and  others  on  the  saline 
waters  over  a  great  area  in  western  Pennsylvania  (§  40). 

The  elimination^  of  sulphate  in  the  form  of  gypsum  from 
evaporating  waters  containing  an  excess  of  chloride  of  calcium 
has  already  been  discussed  in  §  37 ;  but  the  bitterns  resulting 
from  such  a  process  still  retain  small  portions  of  sulphates; 
while  it  is  to  be  remarked  that  the  saline  waters  under  consid- 
eration contain  no  traces  of  sulphates,  and  in  many  instances 
hold  portions  of  baryta  and  strontia,  bases  incompatible  with 
the  presence  of  sulphates.  The  modes  in  which  this  complete 
elimination  of  sulphates  may  be  effected  are  two  in  number. 
The  first  has  already  been  suggested  in  §  10,  and  depends  upon 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  145 

the  deoxidizing  power  of  organic  matters,  which  reduce  the 
sulphates  to  sulphurets.  These  in  their  turn  may  be  converted 
into  carbonates,  the  sulphur  being  separated  either  as  sulphu- 
retted hydrogen  (giving  rise  by  oxidation  to  free  sulphur),  or 
as  insoluble  metallic  sulphurets.  This  reducing  action  not  only 
decomposes  the  soluble  sulphates  of  soda,  lime,  and  magnesia, 
but  also,  as  has  been  pointed  out  in  §  57,  may  extend  to  sul- 
phate of  baryta,  and  thus  sulphuret  or  carbonate  of  baryta  be 
formed.  It  is  the  action  of  these  soluble  baryta-salts  which 
constitutes  the  second  mode  of  desulphatizing  waters  ;  and  this, 
if  we  may  judge  from  the  frequence  with  which  baryta-salts 
occur  in  the  saline  waters  in  question,  appears  to  have  been 
the  most  general  process. 

It  is  a  fact  worthy  of  notice,  that  a  saline  spring  at  Sabre - 
vois,  in  the  province  of  Quebec,  near  Lake  Champlain,  which 
holds  both  baryta  and  strontia  in  solution,  is  at  the  same  time 
slightly  impregnated  with  sulphuretted  hydrogen.  Another 
saline  and  sulphurous  spring,  which  rises  within  ten  feet  of 
this,  contains,  however,  a  portion  of  sulphates.  (Geology  of 
Canada,  page  542.) 

§  62.  I  am  indebted  to  Professor  Croft,  of  Toronto,  for  some 
notes  of  a  recent  examination  by  himself  of  a  saline  of  the  first 
class,  which  contains  at  the  same  time  a  soluble  sulphuret. 
This  water,  from  a  boring  in  Chatham,  Ontario,  at  a  depth  of 
600  feet,  and  about -236  feet  below  the  summit  of  the  Cornifer- 
ous  limestone,  had  a  specific  gravity  of  1039.3,  and  yielded 
for  1,000  parts  about  51  of  solid"  matters.  It  contained  large 
portions  of  chlorides  of  calcium,  and  magnesium,  with  very 
little  sulphate,  traces  of  carbonate,  and  no  free  carbonic  acid. 
The  water,  which  gave  an  alkaline  reaction  with  turmeric,  was 
greenish  in  color,  very  sulphurous  to  the  taste,  and  yielded  a 
purple  color  with  nitroprusside  of  sodium,  and  a  black  precipi- 
tate of  sulphuret  with  a  solution  of  sulphate  of  iron.  A  cur- 
rent of  carbonic  acid  rendered  the  recent  water  opalescent,  and 
by  exposure  to  the  air  it  deposited  sulphur.* 

*  [  For  further  studies  of  waters  of  this  class,  see  the  Supplement  to  this 
paper.] 

7  J 


146  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

§  63.  BORATES.  —  The  reddening  of  the  yellow  color  of  tur- 
meric-paper in  presence  of  free  hydrochloric  acid  affords,  with 
certain  precautions,  the  ordinary  means  for  detecting  small  por- 
tions of  boric  acid.  Most  of  the  waters  of  the  third  and  fourth 
classes,  and  some  of  those  of  the  second,  have  been  tested  in 
this  way,  and  have  never  failed  when  reduced  to  a  small  vol- 
ume, and  acidulated  with  hydrochloric  acid,  to  give  this  re- 
action ;  which  was,  however,  most  marked  with  the  waters  of 
the  fourth  class 

§  64.  I  have  recently  had  an  opportunity  of  examining  from 
California  the  waters  of  a  borax-lake,  which  contains,  beside 
borate  and  carbonate  of  soda,  a  portion  of  chloride,  and  a  little 
silicate,  traces  only  of  phosphate,  and  no  sulphate.  It  held 
in  solution  very  small  quantities  of  earthy  carbonate,  and  was 
remarkable  for  the  large  proportion  of  potassium-salt  which  it 
contains.  The  evaporated  and  fused  saline  residue  was  treated 
by  the  ordinary  methods  for  the  determination  of  the  chlorine, 
carbonic  acid,  and  silica ;  while  the  bases  were  obtained  in  the 
form  of  sulphates  by  the  aid  of  sulphuric  and  hydrofluoric 
acids,  and  afterwards  separated  as  chlorides  by  the  aid  of  chlo- 
ride of  platinum.  From  the  data  thus  obtained  the  following 
ingredients  were  found  by  calculation  for  1,000  parts  of  the 
water :  — - 

Carbonate  of  soda 9.476 

Biborate  of  soda 4.395 

Chloride  of  sodium 1-702 

Carbonate  of  potash 1.818 

Silica  .         •         •         •  0.129 


17.520 

The  potassium,  as  above  determined,  equals  11.46  per  cent 
of  the  bases  weighed  as  chlorides;  another  trial  gave  11.41. 
Although  for  convenience  we  have  represented  the  potassium 
as  carbonate,  it  will  be  seen  that  the  amount  of  chlorine  is 
such  that  it  might,  for  the  greater  part,  have  been  represented 
as  chloride  of  potassium,  with  an  equivalent  portion  additional 
of  carbonate  of  soda. 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  147 

§  65.  CARBONATES.  —  In  examining  in  1847  the  alkaline- 
saline  waters  of  Caledonia,  it  was  found  that  these  contained  a 
quantity  of  carbonic  acid  insufficient  to  form  bicarbonates 
with  the  carbonated  bases  present.  It  was  partly  with  this 
fact  in  view  that,  after  an  interval  of  more  than  seventeen 
years,  I  undertook  the  new  analyses  of  these  waters,  which  in 
§  47  are  given  side  by  side  with  the  earlier  results.  In  these 
later  analyses,  as  there  remarked,  a  slight  excess  of  carbonic 
acid  was  met  with.  In  the  interval  the  springs  had  under- 
gone changes  in  composition,  and  while  the  third  one  still 
retained  in  a  slight  degree  its  alkaline  character,  the  other  two 
had  become  waters  of  the  second  class,  holding,  instead  of 
carbonate  and  sulphate  of  soda,  chloride  of  magnesium,  and 
baryta  salts.  The  amount  of  carbonic  acid  had,  however, 
undergone  but  little  change ;  and  as  will  be  seen  by  compar- 
ing the  figures  below  with  those  in  the  table  in  §  47,  the  slight 
diminution  in  the  first  and  third  corresponds  very  closely  with 
the  falling  off  in  the  amount  of  solid  matters  between  1847  and 
1865 ;  while,  on  the  contrary,  the  augmentation  in  the  amount 
of  carbonic  acid  in  the  second  is  accompanied  with  a  corre- 
sponding increase  in  the  amount  of  fixed  matters  present. 

CARBONIC   ACID   IN   ONE   LITRE   OF   THE   CALEDONIA  WATERS. 

1847.  1865. 

Gas  Spring  .....     .705  grammes.      .671  grammes. 

Saline  Spring 648        "  .664        " 

Sulphur  Spring 590        "  .573       " 

While  the  amounts  of  fixed  matters  and  of  carbonic  acid  in 
the  several  waters  have  undergone  but  little  change,  we  find, 
however,  that  there  has  been  a  great  diminution  in  the  pro- 
portion of  carbonated  bases.  Thus  in  the  Gas  Spring  in 
1847  the  carbonic  acid  required  for  the  neutral  carbonates 
found  in  the  analysis  was  .356,  while  for  the  same  water  in 
1865  only  .278  of  carbonic  acid  was  required.  In  the  Sul- 
phur Spring,  in  like  manner,  the  neutral  carbonates  required 
.449,  or  more  than  three  fourths  of  the  carbonic  acid  present ; 
while  the  falling  off  in  the  amount  of  carbonates  in  1865  is 


148  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

such  that  only  .191  of  carbonic  acid,  or  just  about  one  third 
of  the  carbonic  acid  present,  is  required  for  the  neutral  car- 
bonate. Nor  is  this  change  due  entirely  to  a  less  amount  of 
carbonate  of  soda;  the  carbonates  of  lime  and  magnesia  in 
1847  required  .246,  and  in  1865  only  .153,  of  carbonic  acid. 
The  changed  conditions  which  we  here  meet  with  may  be  ex- 
plained by  supposing  that  the  carbonated  bases  are  due  to  the 
mingling  in  different  proportions  of  neutral  carbonate  of  soda 
(generated  by  the  reaction  indicated  in  §  13)  with  an  earthy- 
saline  water  holding  a  constant  amount  of  free  carbonic  acid  \ 
which,  in  some  cases,  is  more  than  is  required  to  form  bicar- 
bonates,  but  in  others,  as  we  have  seen  above,  shows  a  de- 
ficiency. 

§  66.  If  we  admit,  as  I  have  already  assumed,  that  the 
waters  of  the  second  and  third  classes  have  been  generated  by 
the  mingling  of  solutions  of  carbonate  of  soda  with  waters  of 
the  first'  class,  it  can  readily  be  shown  that  these  solutions 
contained  chiefly  or  exclusively  the  neutral  carbonate.  If  we 
add  a  solution  of  bicarbonate  of  soda  to  earthy-saline  waters 
of  the  first  class,  it  is  easy  to  obtain  solutions  holding  twenty 
grammes  or  more  of  bicarbonate  of  magnesia  to  the  litre  ;  while 
in  none  of  the  natural  waters  of  the  second  class  do  our  anal- 
yses show  the  existence  of  much  over  one  gramme  to  the  litre. 
Again,  if  we  suppose  any  considerable  amount  of  chloride  of 
calcium  to  be  decomposed  by  bicarbonate  of  soda,  the  separa- 
tion of  the  lime  in  the  form  oi"  neutral  carbonate,  and  the 
liberation  of  the  second  equivalent  of  carbonic  acid,  would 
yield  waters  holding  an  excess  of  carbonic  acid  above  that 
required  to  form  the  bicarbonates  of  the  solution.  From  the 
absence  of  such  an  excess,  as  appears  in  the  case  of  the  waters  of 
Caledonia,  Varennes,  and  St.  Leon,  and  from  the  small  amount 
of  bicarbonate  of  magnesia  in  these  waters,  it  may  be  concluded 
that  the  alkaline  salt  whose  addition  has  changed  their  charac- 
ter was  the  neutral  carbonate  of  soda. 

§  67.  Examples  are  not  wanting  of  waters  in  which,  as  in 
those  of  Caledonia  in  1847,  the  carbonic  acid  is  insufficient  to 
form  bicarbonates  (or  even  neutral  carbonates)  with  the  bases 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  149 

uncombined  with  sulphuric  acid  or  chlorine.  Thus,  accord- 
ing to  Pagenstecher  and  Miiller,  the  spring  and  well  waters  of 
Berne  do  not  contain  sufficient  carbonic  acid  for  the  lime 
present,  a  part  of  which  they  suppose  to  be  held  in  solution  as 
a  silicate.  See  Bischof,  Chem.  Geology,  I.  5  ;  who  remarks 
that  Lowig  seems  to  have  observed  the  same  fact  in  the  ther- 
mal spring  of  Pfaffers.  For  further  examples  of  this  kind  see 
Lersch,  Hydro-Chemie,  page  333.  The  carbonic  acid  in  the 
water  of  Toplitz  is,  according  to  him,  not  sufficient  to  form 
bicarbonates  unless  the  silica  present  be  supposed  to  be  com- 
bined with  a  portion  of  bases ;  while  in  the  alkaline  thermal 
spring  of  Bertrich,  according  to  the  analysis  of  Mohr,  a  similar 
deficiency  of  carbonic  acid  exists;  leading  to  the  conclusion 
that  a  part  of  the  earthy  bases  present  is  in  combination  with 
silica  and  organic  matters.  The  existence  of  solutions  holding 
comparatively  large  amounts  of  n^itral  carbonates  of  lime  and 
magnesia,  as  described  in  §  56,  is  not  without  interest  in  this 
connection ;  since  it  at  once  affords  an  explanation  of  the  na- 
ture and  origin  of  all  such  alkaline  waters,  and  waters  deficient 
in  carbonic  acid,  as  contain  earthy  sulphates  and  chlorides. 

§  68.  It  was  found  that  the  waters  of  Chambly  in  1864, 
and  of  the  Sulphur  Spring  of  Caledonia  in  1865,  gave  with 
lime-water  a  precipitate  which  was  soluble  in  an  excess  of  these 
mineral  waters,  but  to  a  much  less  extent  than  in  the  acidu- 
lous saline  water  from  the  High-Rock  Spring  of  Saratoga. 
The  latter,  which  contains  bicarbonate  of  soda,  and  is  highly 
charged  with  carbonic  acid,  turns  to  a  wine-red  the  blue  color 
of  litmus-tincture,  which  is  not  changed  by  the  Chambly  or 
the  Caledonia  water.  The  Saratoga  water,  after  some  time, 
gives  a  feeble  alkaline  reaction  with  dahlia-paper  ;  this  is  more 
distinctly  but  slowly  changed  by  the  Caledonia  water,  and 
almost  immediately  turned  to  green  by  that  of  Chambly. 
This  latter  water  readily  changes  to  brown  yellow  tumeric- 
paper,  which  is  scarcely  affected  by  the  water  of  Caledonia. 

§  69.  SILICA.  —  The  silica  which  exists  in  solution  in  cold 
saline  springs  is  generally  very  small  in  amount,  as  might  be 
expected  from  the  insolubility  of  earthy  silicates,  which  is 


150  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

such  that  superficial  drainage  waters  in  filtering  through  the 
soil  lose  the  silica  which  they  held  in  solution  (§5).  We 
have  further  shown  that  as  a  result  of  this  tendency  to  the 
formation  of  insoluble  silicates,  the  silicate  of  soda  liberated 
in  the  sediments  by  the  decomposition  of  feldspar  generally 
appears  at  the  surface  as  carbonate  of  soda,  having  been  de- 
composed by  earthy  carbonates  (§  13). 

In  two  cases,  however,  considerable  quantities  of  silica  are 
found  dissolved  in  natural  waters.  The  first  is  met  with  where 
the  rapid  solvent  and  decomposing  action  of  heated  waters 
is  exerted  upon  alkaliferous  silicious  minerals  (§  14),  as  seen 
in  springs  like  the  Geysers.  The  second  case  is  that  of  those 
rivers  and  streams  which  drain  surfaces  covered  with  decaying 
vegetation  and  decomposing  silicates,  from  both  of  which  they 
derive  dissolved  silica.  Such  waters  contain  but  small  amounts 
of  solid  matters,  but  the  proportion  of  silica  is  relatively  con- 
siderable, amounting,  as  we  have  seen  in  the  water  of  the 
Ottawa  River,  which  contains,  in  10,000  parts,  0.6116  of 
solid  matters,  to  0.2060,  or  thirty- two  per  cent ;  while  in 
the  St.  Lawrence,  which  contains,  for  the  same  amount  of 
water,  1.6056,  the  silica  equals  .3700,  or  twenty- four  per  cent, 
of  the  solid  ingredients.  The  analysis  by  H.  Ste-Claire  De- 
ville  of  the  river-waters  of  France  show,  in  like  manner,  large 
amounts  of  silica,  which  seem  to  have  been  hitherto  overlooked 
in  the  analyses  of  most  chemists.  '(Ann.  de  Chim.  et  Phys.  (3), 
XXIII.  32.) 

It  will  be  seen  by  a  reference  to  the  tables  of  analyses 
given  in  the  second  part  of  this  paper,  that  in  the  waters  of 
the  second  class  the  amount  of  silica  is  equal  to  from  0.15 
to  0.60  parts  for  100  of  solid  matter.  In  the  alkaline  waters 
of  the  third  and  fourth  classes  its  proportion  is  greater,  and  up 
to  a  certain  point  appears  to  increase  with  that  of  the  carbon- 
ate of  soda The  amount  of  silica  which  these  waters  con- 
tain does  not  in  any  case  exceed  one  or  two  ten-thousandths. 

§  70.  Inasmuch  as  carbonic  acid,  according  to  Bischof 
(Chem.  Geol.,  I.  2),  decomposes  not  only  the  silicates  of  soda, 
but  those  of  lime  and  magnesia,  when  they  are  in  solu- 


IX.]        CHEMISTRY  OF  NATURAL  WATERS.        151 

tion,  it  might  be  supposed  that  the  silica  in  the  above  waters 
exists  either  in  a  free  state  or  as  a  soluble  silicate  with  a  great 
excess  of  acid.  The  latter  view,  especially  in  the  case  of 
magnesia,  is  rendered  probable  by  numerous  experiments 
which  form  a  part  of  the  series  already  mentioned  in  §  41. 
From  these  it  appears  that  free  soluble  silica,  when  mingled 
with  a  solution  of  bicarbonate  of  magnesia,  or  with  the  neutral 
carbonate  dissolved  in  sulphate  of  magnesia  in  the  manner 
described  in  §  56,  whether  separating  immediately  or  by  a 
slower  process  of  gelatinization,  always  carries  down  with  it, 
in  combination,  a  few  hundredths  of  magnesia. 

In  these  experiments,  besides  the  carbonate  of  magnesia, 
sulphate  or  chloride  of  magnesium  was  present ;  but  the  sili- 
cated  natural  waters  now  under  discussion  are  alkaline  from 
the  presence  of  carbonate  of  soda,  and  whatever  partition  of 
bases  between  carbonic  and  silicic  acids  may  exist  in  the  recent 
waters,  we  may  suppose  that  when  they  are  boiled  a  silicate  of 
soda  is  formed,  with  the  expulsion  of  carbonic  acid.  The  sili- 
cate thus  produced  reacts  on  the  earthy  bases  present,  with  the 
production  of  silicates  of  lime  and  magnesia,  which  are  in  part 
precipitated  with  the  earthy  carbonates.  Berzelius  and  Kers- 
ten  long  since  observed  the  separation  of  such  silicates  during 
the  evaporation  of  the  waters  of  Carlsbad  and  of  Marienbad 
(Bischof,  I.  5) ;  while  a  silicate  of  lime  is  said  to  be  deposited 
from  the  waters  of  Wiesbaden.  But  the  silicates  thus  formed 
are  but  partially  precipitated,  —  a  portion  remaining  in  solu- 
tion till  a  late  period  of  the  evaporation.  Dr.  J.  Lawrence 
Smith  long  since  remarked  the  existence  of  a  dissolved  silicate 
of  lime,  apparently  combined  with  soda,  in  the  concentrated 
alkaline  waters  of  Broosa,  in  Asia  Minor.  (Amer.  Jour.  Science 
(2),  XII.  377.) 

Many  facts  in  accordance  with  the  above  were  observed  in 
the  analyses  of  the  waters  described  in  this  paper.  Thus  a 
water  of  Class  III.  from  Belceil,  Quebec,  which  held  in  1,000 
parts  .114  of  silica,  besides  .608  of  carbonate  of  soda,  and  car- 
bonates of  lime,  magnesia,  and  baryta,  when  evaporated  to 
one  tenth  deposited  with  the  carbonates  .050  of  silica,  and  the 


152  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

hydrochloric  solution  of  this  precipitate  became  gelatinous  dur- 
ing evaporation.  The  water  thus  evaporated  still  retained  in 
solution,  besides  a  portion  of  lime,  .064  of  silica ;  which  was 
completely  separated  when  the  alkaline  liquid  was  evaporated 
to  dryness  in  contact  with  the  earthy  carbonates  previously 
precipitated.  When,  however,  these  were  removed  by  filtration, 
it  was  found  that  during  the  evaporation  to  dryness  a  reaction 
took  place  by  which  the  precipitated  silicate  of  lime  was  par- 
tially decomposed,  the  separated  silica  being  redissolved  by  the 
alkaline  carbonate.  In  the  case  of  the  Chambly  water  in  1852, 
which  contained  in  1,000  parts  .073  of  silica,  .042  parts  still 
remained  in  solution  in  the  water  evaporated  to  one  twentieth ; 
and  in  that  of  the  Ottawa  River  when  reduced  to  one  fortieth 
there  still  remained  in  solution  from  10,000  parts  of  water, 
.075  of  silica  and  .028  of  lime.  Similar  results  were  observed 
with  the  alkaline-saline  waters  of  Varennes  and  Fitzroy,  and 
all  of  these  yielded,  by  further  evaporation,  precipitates  con- 
taining silica  and  lime,  and  in  one  instance  magnesia. 

It  is  not,  however,  probably  from  alkaline  waters  like  these, 
but  from  neutral  sea-water,  that  the  silicates  of  magnesia  (and 
of  lime),  which  abound  in  stratified  rocks,  have  been  for  the 
most  part  formed.  See  further  on  this  point,  §  41. 

§  71.  ORGANIC  MATTERS.  —  In  §  44  we  have  described  some 
of  the  reactions  of  the  organic  matter  found  in  the  Chambly 
water,  and  it  is  to  be  remarked  that  small  portions  of  a  similar 
substance  were  found  in  all  alkaline  waters  of  the  third  and 
fourth  classes,  and  caused  them  to  become  brownish  when 
evaporated  to  a  small  volume.  This,  it  has  been  already  sug- 
gested, may  have  a  superficial  origin,  the  organic  matters  car- 
ried down  by  surface-waters  being  kept  in  solution  by  the 
alkaline  salts ;  it  is  not,  however,  impossible  that  this  same 
menstruum  may  remove  the  organic  matters  which  abound  in 
the  pyroschists  and  other  materials  of  organic  origin  in  the 
ancient  rocks.  Thus,  for  example,  the  coprolites  of  the  lower 
palaeozoic  limestones  contain  so  much  animal  matter  as  to  evolve 
an  odor  like  burning  horn  when  exposed  to  heat.  (Geology  of 
Canada,  462.) 


IX.]  CHEMISTRY   OF   NATURAL  WATERS.  153 

The  Ottawa  water  (§  46),  when  boiled  to  one  tenth,  deposits 
a  precipitate  in  small  bright  brown  iridescent  scales.  This  was 
found  to  contain  silica,  carbonate  of  lime,  and  a  small  portion 
of  an  organic  substance  which  was  dissolved  in  dilute  potash 
ley.  The  brown  solution  thus  obtained  was  not  disturbed  by 
acetic  acid  and  acetate  of  copper,  but  by  the  subsequent  ad- 
dition of  carbonate  of  ammonia  yielded  a  white  precipitate. 
The  concentrated  water  retained  a  large  proportion  of  organic 
matter,  and  when  reduced  to  a  small  bulk  was  dark  brown, 
alkaline  to  turmeric-paper,  and  continued  by  evaporation  to  de- 
posit opaque  films  of  silicate  of  lime.  The  finally  dried  residue 
was  dark  brown  in  color,  and  carbonized  by  heat,  burning  like 
tinder  and  diffusing  an  agreeable  odor.  The  residue  of  10,000 
parts  dried  at  300°  F.  weighed  .6974,  and  lost  by  gentle 
ignition  .1635,  consisting  partly  of  organic  matter.  JSTo  chemi- 
cal examination  was  made  of  this  matter  held  in  solution  by 
the  concentrated  water.  From  the  late  researches  of  Peligot, 
however,  it  appears  that  the  organic  matter  precipitated  by 
nitrate  of  lead  from  the  water  of  the  Seine  has  nearly  the  com- 
position of  the  apocrenic  acid  of  Berzelius.  It  gave,  on  analy- 
sis, carbon  53.1,  hydrogen  2.7,  nitrogen  2.4,  oxygen  41.8,  and 
is  evidently  related  to  the  soluble  form  of  vegetable  humus. 
(Comptes  Eendus,  April  25,  1864.)  When  exposed  to  heat 
this  substance  evolved  ammonia,  with  the  odor  of  burning 
wool,  while  the  organic  matter  from  the  Ottawa  water,  on  the 
contrary,  gave  an  odor  like  burning  turf. 


GEOLOGICAL  POSITIONS   OF  THE  PRECEDING  WATERS. 

§  72.  The  palaeozoic  area  from  which  the  above-described 
waters  are  derived  includes  the  basin  of  the  St.  Lawrence  from 
Lake  Erie  to  near  Quebec,  with  its  extensions  in  the  valleys  of 
the  Lower  Ottawa  and  Lake  Champlain.  Over  the  greater  part 
of  this  champaign  region  the  strata  are  nearly  horizontal,  but 
towards  its  eastern  part  there  are  various  minor  folds  and  un- 
dulations. It  is  in  this  disturbed  region  that  by  far  the  greater 


154  CHEMISTRY   OF   NATURAL   WATERS.  [IX. 

number  of  the  mineral  springs  already  described  occur;  and 
although  it  is  often  difficult  to  establish  the  presence  or  to  trace 
the  extent  of  faults  in  the  strata,  on  account  of  the  alluvial  de- 
posits which  generally  cover  the  palaeozoic  strata  of  the  region, 
it  is  apparent  that  in  a  great  number  of  cases  the  mineral  springs 
occur  along  the  lines  of  disturbance,  and  it  is  probable  that  a  con- 
stant relation  of  this  kind  exists.  The  great  western  portion  of 
the  basin,  which  is  less  disturbed  than  its  eastern  part,  presents 
but  few  mineral  springs  ;  yet  the  wells  of  strongly  saline  water 
which  have  been  obtained  by  boring  at  Kingston,  Hallowell, 
St.  Catherine's,  Chatham,  and  elsewhere  in  Ontario,  show  that 
the  undisturbed  rocky  strata  are  charged  with  saline  matters. 
For  a  better  understanding  of  the  relations  of  these  waters,  a 
list  of  the  paleozoic  formations  in  which  the  mineral  springs 
here  described  occur  is  given  below,  numbered  in  ascending 
order.  [Of  these  the  first  six  correspond  to  the  first  and  second 
palasozoic  faunas,  the  Cambrians  of  Sedgwick  and'  the  Lower 
Silurian  of  Murchison,  while  7-12  include  the  third  fauna, 
or  true  Silurian,  and  the  remaining  three  the  lower  part  of  the 
Devonian  series.] 

Palceozoic  Formations  of  the  St.  Lawrence  Basin. 

15.  HAMILTON, — shales. 

14.  COENIFEROTTS, — limestone. 

13.  0  RISK  ANY,  —  sandstone. 

12.  LOWER  HELDERBERG,  — limestone. 

11.  ONONDAGA,  OR  SALINA,  —  dolomite  and  shales. 

10.  GUELPH, — dolomite. 

9.  NIAGARA,  —  dolomite. 

8.  CLINTON,  —  dolomite  and  shales. 

7.  MEDINA,  —  sandstone. 

6.  HUDSON  RIVER,  —  shales. 

5.  UTICA,  —  shales. 

4.  TRENTON,  —  limestone. 

3.  CHAZY,  —  limestone. 

2.  CALCIFEROUS,  —  dolomite. 

1.  POTSDAM,  —  sandstone. 

§  73.    Of  the  above  series  the  Trenton  group  includes  the 
Birds-eye  and  Black  Paver  limestones,  as  well  as  the  Trenton 


IX.]        CHEMISTRY  OF  NATURAL  WATERS.        155 

limestone  of  the  New  York  geologists,  and  is  non-magnesian, 
enclosing  beds  of  chert,  silicified  fossils,  and  petroleum ;  in  all 
of  which  characters  it  resembles  the  Corniferous  limestone 
above.  In  like  manner  the  Potsdam  is  represented  by  the 
Hudson  River  and  Medina  formations,  while  the  gypsiferous 
dolomite  of  the  so-called  Calciferous  sand-rock  corresponds  to 
the  great  mass  of  dolomite  which  constitutes  Nos.  9,  10,  and 
11,  and  includes  the  gypsum  and  the  salt-bearing  strata  of 
the  Onondaga  formation.  These  repetitions  of  similar  strata 
mark  successive  recurrences  of  similar  geological  and  geo- 
graphical conditions,  which  form  great  cycles  in  the  history  of 
the  continent. 

§  74.  [Within  the  eastern  border  of  this  basin,  stretching 
along  the  western  base  of  the  Green  Mountains,  and  thence 
northeast  to  Quebec,  and  beyond  it  on  the  southeast  shore  of 
the  St.  Lawrence,  is  spread  a  great  series  including  about  7,000 
feet  of  limestones,  dolomites,  shales,  and  sandstones.  These 
rocks,  which  are  more  or  less  disturbed,  constitute  what  Logan 
has  called  the  Quebec  group,  and  are  the  Taconic  of  Emmons, 
or  the  Primal  and  Auroral  of  Rogers,  containing  organic  remains 
of  the  first  palaeozoic  fauna,  and  corresponding  to  the  Lower 
and  Middle  Cambrian  of  Sedgwick,  of  which  the  first  three 
formations  in  the  above  table  are  but  incomplete  and  littoral, 
or  shallow- water  deposits.  (See  further,  paper  XV.,  part  3.)] 

None  of  the  waters  described  in  the  present  paper  belong  to 
this  Quebec  group,  which,  nevertheless,  presents  several  mineral 
springs,  some  of  which  are  described  in  the  Geology  of  Canada. 
Of  these,  the  salines  of  Cacouna,  Green  Island,  Riviere  Ouelle, 
and  Ste.  Anne  de  la  Pocatiere  are  bitter  waters  belonging  to 
the  first  class ;  while  a  sulphurous  spring  at  the  latter  place, 
and  another  at  Quebec,  are  alkaline  waters  of  the  fourth  class. 

§  75.  Of  the  waters  of  the  region  which  is  considered  in 
this  paper,  many  have  been  qualitatively  analyzed  which  are  not 
here  described.  Including  two  from  Vermont,  twenty-one  alka- 
line waters  of  the  third  and  fourth  classes  have  been  exam- 
ined. Of  these,  as  already  stated,  the  waters  of  Caledonia  rise 
from  the  Trenton  group,  and  that  of  Fitzroy  from  the  Chazy  or 


156  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

Calciferous,  while  two  others,  at  Ste.  Martine  and  Rawdon, 
appear  to  have  their  source  in  the  Potsdam.  All  the  other 
waters  of  these  two  classes  issue  from  the  Hudson  Eiver  shales, 
with  the  exception  of  those  of  Varennes  and  Jacques  Cartier, 
which  seem  to  rise  from  the  Utica  formation. 

Of  the  waters  of  the  second  class,  of  which  about  thirty  have 
been  examined,  some  five  or  six  issue  from  the  shale  formations 
Xos.  5  and  6,  but  all  the  others  are  from  the  underlying  lime- 
stones. The  bitter  salines  of  the  first  class  flow  from  the  lime- 
stones of  the  Trenton  group,  with  the  exception  of  one  at 
Ancaster,  which  is  from  a  well  sunk  in  the  Niagara  formation, 
and  that  of  St.  Catherine's,  from  a  boring  carried  through  the 
Medina  down  into  the  Hudson  River  shales.  The  source  of 
both  of  these  is  probably,  like  that  of  the  other  very  similar 
waters,  the  underlying  limestones. 

§  76.  From  this  distribution  of  the  waters  of  the  first  four 
classes  it  would  appear  that  the  source  of  the  neutral  salts, 
which  consist  of  alkaline  and  earthy  chlorides,  is  in  the  lime- 
stones and  other  strata  from  the  Potsdam  to  the  Trenton  inclu- 
sive, while  the  alkaline  carbonates  are  derived  from  the  argilla- 
ceous sediments  which  make  up  the  Utica  and  Hudson  River 
formations.  The  sediments  are  never  deficient  in  alkaline  sili- 
cates, whose  slow  decomposition  yields  to  infiltrating  waters 
(§13)  the  alkaline  carbonates  which  characterize  the  mineral 
springs  of  the  fourth  class.  These,  mingling  in  various  propor- 
tions with  the  brines  which  rise  from  the  limestones  beneath, 
produce  the  waters  of  the  second  and  third  classes  in  the  man- 
ner already  explained.  The  appearance  of  several  springs  of 
the  third  class,  as  those  of  Caledonia  and  Fitzroy,  from  these 
lower  limestones,  is  not  surprising,  when  it  is  considered  that 
the  Chazy  formation  in  the  Ottawa  Valley  includes  a  considera- 
ble thickness  of  shales,  sandstones,  and  argillaceous  limestones, 
approaching  in  composition  to  the  sediments  of  the  Hudson 
River  formation. 

§  77.  As  an  evidence  that  the  different  classes  of  waters 
have  their  origin  in  different  strata,  may  be  cited  the  fact  that 
springs  very  unlike  in  composition  are  often  found  in  close 


IX.]        CHEMISTRY  OF  NATURAL  WATERS.        157 

proximity,  and  apparently  rising  from  a  common  fissure  or  dis- 
location. Thus  in  the  seigniories  of  JSTicolet  and  La  Baie  du 
Febvre,  I  have  examined  six  springs,  all  of  which  rise  through 
the  Utica  formation  along  a  line,  in  a  distance  of  about  eight 
miles.  Of  these  springs  two  belong  to  the  second,  two  to  the 
third,  and  two  to  the  fourth  class ;  these  last  being  probably 
derived  entirely  from  the  shales,  while  the  others  have  their 
source  in  the  underlying  limestones,  and  are  more  or  less  modified 
in  their  ascent.  Again,  at  Sabrevois,  within  a  few  feet  of  each 
other,  are  two  springs  of  the  second  class,  of  which  one  contains 
salts  of  baryta  and  strontia,  and  the  other  soluble  sulphates. 
In  like  manner  at  Ste.  Anne  de  la  Pocatiere  a  spring  of  the 
second  class  and  one  of  the  fourth  are  found  not  far  apart. 
The  springs  of  Caledonia  offer  another  and  not  less  remarkable 
example.  In  1847  there  were  to  be  seen,  not  far  from  a  spring 
of  the  second  class,  three  others  of  the  third  class  very  near  to- 
gether, one  of  them  sulphurous,  but  all  sulphated,  and  differing 
in  the  proportions  of  carbonate  of  soda  present.  In  1865, 
while  one  of  these  still  retained  its  character  of  a  sulphurous 
sulphated  water  of  the  third  class,  the  others  were  changed  to 
waters  of  the  second  class,  and  held  salts  of  baryta  in  solution. 
These  relations,  which  we  have  already  pointed  out  (§  47),  not 
only  show  waters  holding  incompatible  salts  issuing  from  dif- 
ferent strata  along  the  same  fissure,  but  mingling  in  such  vary- 
ing proportions  as  to  produce  from  time  to  time  changes  in  the 
constitution  of  the  resulting  springs. 

§  78.  The  temperature  of  none  of  the  springs  which  we  have 
here  described  exceeds  53°,  which  has  been  observed  for 
two  springs  at  Chambly,  about  twelve  miles  from  Montreal 
(§  44).  No  other  springs  in  Canada  are  known  to  present  so 
high  temperature,  unless  possibly  the  acid  waters  of  the  fifth 
class  (§  48).  St.  Loon  spring  was  found  to  be  46°,  while  that 
of  Caxton,  near  the  last,  and  like  it  of  Class  II.,  was  49°  F. 

§  79.  The  extended  series  of  analyses  which  we  have  given 
in  the  preceding  pages  presents  many  points  of  interest.  Xo- 
where  else,  it  is  believed,  has  such  a  complete  systematic  exam- 
ination of  the  waters  of  a  region,  and  of  a  great  geological 


158  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

series,  been  made.  Additional  importance  is  given  to  these 
results  by  the  fact  that  the  waters  are  all  derived  from  palaeozoic 
strata.  We  are  thus  enabled  to  compare  these  saline  mate- 
rials of  an  ancient  period  with  those  which  issue  from,  and  in 
many  cases  owe  their  saline  impregnation  to,  strata  of  com- 
paratively modern  origin  (§  39). 

It  is  a  consideration  not  without  interest,  that  the  valley  of 
the  St.  Lawrence  might,  under  different  meteorological  condi- 
tions, become  a  region  abounding  with  saline  lakes  affording 
sea-salt,  natron,  and  borax,  the  results  of  the  evaporation  of  the 
numerous  saline  and  alkaline  springs  which  have  here  been 
described. 


SUPPLEMENT. 

[From  the  Report  of  the  Geological  Survey  of  Canada  for  1863-66,  pages  272-277.] 

As  further  examples  of  saline  waters  of  the  first  class,  such  as 
are  described  in  §§  35-40  of  the  preceding  paper,  I  here  give 
the  results  of  the  analyses  of  two  from  western  Ontario,  both 
which  were  met  with  in  boring  for^  petroleum.  The  first  of 
these  is  from  a  well  on  Manitoulin  Island  in  Lake  Huron,  and 
was  found  at  a  depth  of  192  feet  from  the  surface,  after  pass- 
ing through  the  black  slates  of  the  Utica  formation,  and  for 
sixty  feet  in  the  underlying  Trenton  limestone.  The  water 
was  intensely  bitter  and  saline  to  the  taste ;  it  contained  no 
trace  of  sulphates,  nor  yet  of  barium  nor  strontium.  It  was 
not  examined  for  bromides  or  iodides,  which,  however,  were 
probably  present.  The  analysis  of  this  water  gave,  for  1,000 
parts,  as  follows  :  — 

Chloride  of  sodium 4.800 

Chloride  of  potassium .792 

Chloride  of  calcium 12.420 

Chloride  of  magnesium    ......  3.650 


21.662 


IX.]        CHEMISTRY  OF  NATUBAL  WATERS.        159 

This  water  is  remarkable  for  the  amount  of  chloride  of 
calcium  which  it  contains,  equal  to  more  than  one  half  of  the 
solid  contents,  a  much  larger  proportion  than  in  any  of  the 
bitter  saline  waters  hitherto  examined  in  Canada,  or  elsewhere. 
In  most  waters  of  this  class,  the  proportion  of  chloride  of 
potassium  (as  shown  in  §  52)  is  small,  rarely  attaining  to  one 
hundredth  of  the  alkaline  chlorides;  but  in  the  Manitoulin 
water  it  amounts  to  not  less  than  16.6  per  cent  of  these  or 
more  than  3.7  per  cent  of  the  entire  solid  matters,  a  propor- 
tion as  great  as  in  modern  sea- water.  This  peculiarity,  not 
less  than  the  absence  of  sulphates,  would  lead  us  to  suspect 
that  this  water  may  be  derived,  by  dilution,  from  an  ancient 
bittern,  from  which,  owing  to  the  excess  of  lime  in  the  primi- 
tive seas,  the  sulphates  have  been  eliminated  in  the  form  of 
gypsum,  in  the  process  of  evaporation.  Further  analyses  of 
waters  from  this  region  are  needed  to  complete  their  history. 

The  second  water  to  be  noticed  is  from  a  well  sunk  at 
Both  well,  Ontario,  for  petroleum,  in  1865.  At  a  depth  of 
475  feet  from  the  surface,  and  probably  at  or  near  the  base  of 
the  Corniferous  limestone,  a  copious  spring  was  met  with,  which 
rose  to  the  surface,  and  on  the  16th  of  September,  1865,  was 
yielding  at  the  rate  of  about  700  gallons  per  hour  of  bitter,  very 
sulphurous  water,  with  a  little  petroleum.  The  temperature 
of  this  water  was  54°  F.,  or  about  7°  above  the  mean  tempera- 
ture of  the  region,  which  is  traversed  by  the  isothermal  line  of 
47°  F.  The  water  was  placed  in  carefully  filled  and  well-corked 
bottles,  which  were  laid  on  their  sides,  and  thus  transported  to 
my  laboratory  at  Montreal.  Its  specific  gravity  was  1020.9, 
and  that  of  another  portion  collected  five  days  later,  on  the 
21st  September,  was  1021.1.  The  water,  which  at  the  well 
was  transparent  and  colorless,  was  found  on  opening  the 
bottles  to  have  become  slightly  yellowish.  By  further  expos- 
ure to  the  air  it  turned  greenish-yellow  from  the  formation  of  a 
persulphide,  and  soon  became  coated  with  a  film  of  sulphur, 
the  liquid  after  a  while  again  growing  colorless.  The  color 
was  at  once  destroyed  by  a  little  hydrochloric  acid,  the  water 
becoming  opalescent  from  the  separation  of  sulphur.  The 


160  CHEMISTRY  OF  NATURAL  WATERS.  [IX. 

recent  water  was  feebly  alkaline  to  litmus,  but  did  not  affect 
the  color  of  curcuma-paper. 

These  characters  showed  the  recent  water  to  contain  a  solu- 
ble monosulphide,  whose  presence  was  further  indicated  by  the 
addition  of  a  solution  of  green  vitriol,  which  gave  an  abun- 
dant precipitate  of  sulphide  of  iron.  Nitroprusside  of  sodium 
gave  a  fine  purple  color  with  the  water,  which  was  rendered 
more  intense  by  the  previous  addition  of  a  little  caustic  soda. 

When  boiled,  the  recent  water  evolves  an  abundance  of  sul- 
phuretted hydrogen,  and  after  twenty  minutes  of  ebullition 
the  reaction  of  sulphur  disappears  from  the  water ;  which  be- 
comes turbid,  from  the  separation  of  a  hydrate  of  magnesia, 
readily  soluble  in  a  cold  solution  of  sal-ammoniac.  Crystals  of 
gypsum  are  also  deposited  during  the  boiling.  This  volatiliza- 
tion of  the  sulphur  is  evidently  due  to  the  well-known  de- 
composition of  sulphide  of  magnesium,  by  boiling,  into  hydrated 
oxide  of  magnesium  and  sulphuretted  hydrogen  gas.  It  was, 
however,  a  question  whether  the  whole  of  the  sulphur  in  the 
recent  water  existed  as  a  sulphide  of  sodium  or  magnesium,  or 
whether  a  portion  was  present  as  sulphide  of  hydrogen,  giving 
with  the  former  a  double  sulphide  MgS,HS.  This  problem, 
of  considerable  delicacy,  can  only  be  solved  by  indirect  means. 
For  the  determination  of  the  whole  amount  of  sulphide  in  the 
recent  water,  having  at  the  well  no  other  suitable  reagent,  I 
added  to  two  bottles  of  the  water  a  few  grammes  each  of  sul- 
phate of  copper  ;  the  sulphide  thus  precipitated  was  afterwards 
collected  and  analyzed.  In  that  from  one  bottle  the  amount 
of  sulphur  in  the  precipitate  was  directly  determined,  while  in 
the  other  it  was  deduced  from  that  of  the  copper.  These  two 
results  gave,  respectively,  .460  and  .464  grammes  of  sulphur  to 
the  litre  of  water,  the  mean  of  which,  .462,  is  equal  to  .491 
grammes  of  sulphide  of  hydrogen.  In  addition  to  these,  a  de- 
termination was  made  with  the  water  brought  to  the  labora- 
tory. This,  when  mingled  with  an  acid  solution  of  terchloride 
of  arsenic,  gave  a  quantity  of  tersulphide  of  arsenic  equal  to 
.460  grammes  of  sulphuretted  hydrogen,  indicating  a  slight 
loss  of  sulphur. 


IX.]  CHEMISTRY  OF  NATURAL  WATERS.  161 

"When  a  double  sulphide  of  sodium  and  hydrogen  exists  in 
an  alkaline  water,  it  is  possible,  by  boiling,  to  destroy  the 
compound,  and  by  expelling  the  sulphide  of  hydrogen,  to  deter- 
mine the  amount  of  sulphur  which  is  present  as  a  fixed  mono- 
sulphide.  But  when  the  double  sulphide  has  a  base  of  mag- 
nesium, or  exists  in  a  water  containing  an  excess  of  a  soluble 
magnesian  salt,  the  ready  decomposition  of  sulphide  of  magne- 
sium will  cause  the  whole  of  the  sulphur  to  be  carried  off  by 
boiling,  in  the  form  of  sulphuretted  hydrogen,  with  separation 
of  hydrate  of  magnesia,  as  is  the  case  of  the  Bothwell  water. 
The  following  experiment  was,  however,  devised,  which  shows 
the  existence  of  a  double  sulphide  in  this  water,  and  at  the 
same  time  enables  us  to  suggest  a  method  which  may  probably 
be  used  for  the  complete  analysis  of  this  and  of  similar  waters. 

It  is  well  known  that  solutions  of  alkaline  and  earthy  sul- 
phides dissolve  tersulphide  of  arsenic,  yielding  double  sul- 
phides or  sulpharsenites,  whose  formula,  for  the  alkaline  bases, 
is,  according  to  Berzelius,  AsS8,3MS,  and  for  the  earthy  bases, 
AsSj,2MS.  If  these  protosulphides  are  combined  with  sul- 
phide of  hydrogen,  forming  double  salts,  MS,HS,  the  latter 
will  be  displaced  by  the  arsenious  sulphide.  The  presence  of 
such  a  compound  in  the  Bothwell  water  was  shown  by  adding 
to  it  freshly  precipitated  and  carefully  washed  tersulphide  of 
arsenic,  which  was  rapidly  dissolved,  with  an  abundant  disen- 
gagement of  sulphuretted  hydrogen  gas.  The  solution,  after 
digestion  for  a  few  minutes  at  36°  Centigrade,  was  filtered 
from  the  excess  of  undissolved  sulphide,  and  supersaturated 
with  acetic  acid,  which  threw  down  a  quantity  of  sulphide  of 
arsenic  equal  to  .925  grammes  to  the  litre.  Another  portion 
of  the  same  bottle  of  water,  treated  with  an  acid  solution  of 
terchloride  of  arsenic,  gave  an  amount  of  sulphide  of  arsenic 
equal  to  1.110  grammes  to  the  litre^ 

If  now  we  suppose  the  dissolved  sulphide  of  arsenic  in  the 
experiment  above  described  to  have  been  in  the  state  of  a 
sulpharsenite  of  magnesium,  AsS,,2MgS,  in  which  the  amount 
of  sulphur  in  the  two  terms  is  as  3  :  2,  we  should  have 
(3:2::  .925  :  .617)  .617  grammes  of  the  sulphide  of  arsenic 


162  CHEMISTRY  OF  .NATURAL  WATERS.  [IX. 

in  the  last  determination  derived  from  the  magnesian  sulphide, 
leaving  1.110  —  .617  =  .49  3  grammes  due  to  the  sulphide  of 
hydrogen  in  the  water.  If,  however,  the  arsenious  sulphide  was 
dissolved  as  sulpharsenite  of  sodium,  AsS3,3NaS,  in  which 
the  sulphur  ratio  is  3  :  3,  we  have  evidently  .925  of  sulphide 
of  arsenic  derived  from  the  sulphide  of  sodium  in  the  water, 
leaving  only  .185  to  be  formed  by  the  sulphide  of  hydrogen. 
Since,  however,  the  water  contains  large  proportions  alike  of 
the  chlorides  .of  sodium,  calcium,  and  magnesium,  we  may 
suppose  that  there  is  a  partition  of  bases,  so  that  portions  both 
of  alkaline  and  earthy  sulphides  may  be  present.  The  excess 
of  magnesian  chloride  would  in  any  case  produce  the  complete 
decomposition,  observed  in  boiling,  into  magnesia  and  sul- 
phuretted hydrogen. 

Two  questions  then  suggest  themselves  in  the  analysis  of 
this  water.;  the  first  as  to  the  relative  proportions  of  sulphide 
of  hydrogen  and  the  monosulphides  of  fixed  bases,  and  the 
second  as  to  the  base  or  bases  of  these  fixed  sulphides.  To 
resolve  the  first  question,  the  following  method  suggests  itself : 
add  to  one  measured  portion  of  the  water,  at  the  spring,  an 
acid  solution  of  terchloride  of  arsenic,  by  which  the  whole 
amount  of  sulphide  in  the  water  may  be  determined.  To 
another  portion  add  a  neutral  solution  of  chloride  of  zinc  or 
protochloride  of  iron,  which  will  precipitate  the  sulphur  of 
the  fixed  sulphides  only,  liberating  the  sulphide  of  hydrogen. 
Having  removed  this  by  boiling,  or  by  filtration,  the  insoluble 
metallic  sulphide  might  be  treated  with  a  mixture  of  a  solution 
of  terchloride  of  arsenic  and  hydrochloric  acid,  by  which  means 
its  sulphur  would  be  obtained  as  sulphide  of  arsenic,  whose 
weight,  as  compared  with  that  from  the  former  determination, 
would  show  the  quantities  both  of  fixed  and  volatile  sulphide 
in  the  water.  In  connection  with  this,  a  determination  of  the 
solvent  power  of  the  recent  water  for  tersulphide  of  arsenic 
would  afford  the  means  of  solving  the  second  question. 

For  the  analysis  of  the  Bothwell  water,  the  sulphate  of  lime 
being'determined  by  the  amount  of  sulphuric  acid,  the  chlorides 
were  calculated  from  the  quantities  of  bases  present,  the  sul- 


IX.]        CHEMISTRY  OF  NATURAL  WATERS.        163 

phur  corresponding  to  the  dissolved  sulphide  of  arsenic  being 
provisionally  estimated  as  sulphide  of  sodium.  We  have  thus 
for  1,000  parts  of  the  water,  as  follows  :  — 

Chloride  of  sodium 14.4460 

Chloride  of  potassium  ....  .3350 

Chloride  of  calcium          ....  3.1830 

Chloride  of  magnesium          .         .         .  5.7950 

Sulphate  of  lime 3.0580 

Sulphide  of  sodium       .         .                  .  .8797  j  _  460Q 
Sulphide  of  hydrogen       .... 


Waters  like  this  of  Bothwell  are  not  unfrequently  met  with  in 
the  borings  in  the  adjacent  region,  especially  in  those  in  Ennis- 
killen,  where  in  a  well  at  Petrolia,  at  a  depth  of  471  feet  from 
the  surface,  and  171  feet  from  the  summit  of  the  Corniferous 
limestone,  a  copious  spring  of  this  kind  was  struck,  which 
filled  the  bore  of  the  well,  and  flowed  in  a  copious  stream, 
bearing  with  it  a  little  petroleum.  It  was  a  very  bitter  sa- 
line, which  dissolved  sulphide  of  arsenic,  and  gave  a  purple 
color  with  nitroprusside  of  sodium,  but  was  less  strongly  sul- 
phurous than  that  of  Bothwell.  Waters  apparently  similar 
are  pumped  from  several  of  the  oil-wells  in  the  vicinity. 

From  the  facts  observed  in  these  wells  of  Bothwell,  Petrolia, 
and  that  of  Chatham  mentioned  already  in  §  62,  it  would  ap- 
pear that  these  waters  occur  beneath  the  Corniferous  limestone, 
and  in  the  upper  part  of  the  Onondaga  or  saliferous  formation  of 
the  region.  The  great  density  of  that  of  Chatham,  which  much 
surpasses  that  of  sea -water,  shows  it  to  be  derived  from  a  bittern, 
the  result  of  the  evaporation  of  the  waters  of  an  ancient  sea. 
The  sulphurous  impregnation  is  doubtless  to  be  ascribed  to  the 
reducing  action  of  hydrocarbonaceous  matters  upon  the  sul- 
phates which  these  waters  contain.  It  may  therefore  happen 
that  the  proportion  of  sulphides  in  them  will  be  found  subject 
to  considerable  variations. 


164  POROSITY  OF  ROCKS.  [IX. 


APPENDIX. 

ON    THE   POROSITY   OF   ROCKS. 
[From  the  Report  of  the  Geological  Survey  of  Canada  for  1863-66,  pages  281-283.] 

ALL  rocks  are  more  or  less  porous,  and  most  uncrystalline  sedi- 
mentary ones  possess  this  character  to  a  very  considerable  degree. 
Such  rocks  when  taken  from  the  quarries  are  more  or  less  com- 
pletely saturated  with  water,  from  which,  indeed,  they  have  never 
been  free  since  the  time  of  their  formation.  This  water  they  gradu- 
ally lose  when  exposed  to  the  air,  and,  as  is  well  known  in  the  case 
of  many  building-stones,  become  much  harder  than  before.  The 
porosity  of  rocks  is  of  considerable  importance  in  relation  to  their 
value  as  building  materials.  The  open  spaces  between  the  particles 
diminish  the  cohesion  of  the  mass,  and,  in  addition  to  this,  the  water 
held  in  the  pores  of  a  rock,  when  exposed  to  cold,  tends,  by  its  ex- 
pansion in  freezing,  to  disintegrate  the  mass,  and  cause  it  to  crumble, 
a  consideration  of  much  importance  in  a  cold  climate.  Other  things 
being  equal,  it  may  probably  be  said  that  the  value  of  a  stone  for 
building  purposes  is  inversely  as  its  porosity  or  absorbing  power. 

The  study  of  the  porosity  of  rocks  is,  moreover,  of  much  interest 
from  a  geological  point  of  view.  As  I  have  elsewhere  endeavored 
to  show  (ante,  pages  103  and  163),  the  origin  of  most  of  the  muriated 
saline  springs  is  to  be  sought  in  old  sea- waters  and  bitterns  impris- 
oned in  ancient  sedimentary  strata,  which  must  now  hold  in  their 
pores  an  amount  of  water  bearing  a  considerable  proportion  to 
the  entire  volume  of  the  present  ocean.  The  observations  here 
given  were  made  in  1864,  with  reference  to  both  of  the  above 
considerations. 

The  method  of  investigation  was  as  follows  :  Small  broken  frag- 
ments of  the  rocks  —  generally  from  twenty  to  forty  grammes  in 
weight  —  were  selected,  and  freed  from  scales  or  loose  grains,  which 
might,  by  falling  off  during  the  experiment,  vitiate  the  results. 
These  specimens  were  carefully  dried  at  about  200°  F.,  till  they 
ceased  to  lose  weight ;  most  of  them  had,  however,  been  long  pre- 
served in  a  dry  room,  and  were  found  to  be  nearly  free  from  moist- 
ure. The  weight  of  these  having  been  determined,  they  were  placed 
with  their  lower  portions  in  water,  and  allowed  to  remain  for  some 
hours,  after  which  they  were  covered  with  water  and  placed  under 


IX.]  POROSITY  OF  ROCKS.  165 

the  exhausted  receiver  of  an  air-pump,  by  which  process  a  large 
portion  of  air  was  removed.  The  exhaustion  of  the  receiver  was 
several  times  repeated,  at  intervals,  until  the  portions  of  rock  were 
as  nearly  as  possible  saturated,  and  bubbles  ceased  to  escape  on 
further  exhaustion.  They  were  then  removed,  carefully  wiped 
with  blotting-paper,  and  again  weighed,  —  first  in  air,  and  then 
in  water.  These  three  weighings  furnish  the  data  necessary  for 
determining,  — 

I.   The  specific  gravity  of  the  mass,  or  the  apparent  specific  gravity, 

compared  with  water  as  unity. 
II.  The  specific  gravity  of  the  particles,  or  real  specific  gravity. 

III.  The  volume  of  water  absorbed  by  100  volumes  of  the  rock. 

IV.  The  weight  of  water  absorbed  by  100  parts  by  weight  of  the  rock. 

The  loss  in  weight  of  the  saturated  rock  when  weighed  in  water, 
being  equal  to  that  of  the  volume  of  water  displaced-  by  the  mass, 
enables  us  to  determine  the  specific  gravity  of  the  latter  ;  while  this 
loss  in  weight,  less  the  weight  of  the  water  absorbed  by  the  mass, 
gives  the  true  volume  of  water  displaced  by  its  particles,  and  hence 
the  means  of  determining  their  specific  gravity.  The  division,  by 
the  volume  of  water  displaced,  of  the  amount  of  water  absorbed, 
gives  the  absorption  by  volume  ;  and  the  division  of  the  weight 
of  the  water  absorbed  by  that  of  the  dry  mass,  the  absorption  by 
weight :  — 

a  =  the  weight  of  the  dry  rock. 

b  =  the  weight  of  water  which  the  rock  can  absorb. 

c  =  the  loss  of  weight,  in  water,  of  the  saturated  rock. 

We  have  then  the  following  equations  :  —  , 

I.  c  :  a  ::  1.000  :  x  =  specific  gravity  of  the  mass,  or  apparent  specific 

gravity,  water  being  1.000. 

II.  c-  b  :  a  ::  1.000  :  x  =  specific  gravity  of  the  particles,  or  real  specific 
gravity,  water  being  1.000. 

III.  c:  b  ::  IQQ  :  x  =  volume  of  water  absorbed  by  100  volumes  of  the 

rock. 

IV.  a  :  b  ::  100  :  x  =  weight  of  water  absorbed  by  100  parts  by  weight 

of  the  rock. 

From  these  the  following  table  has  been  calculated,  the  results 
given  under  the  last  four  columns  corresponding  to  the  four  equa- 
tions above  :  —  * 

*  A  similar  series  of  results  will  be  found  in  a  report  to  the  British  House 
of  Commons,  in  1839,  *>y  Messrs.  Barry,  Delabeche,  and  Smith,  made  with 


166  POROSITY   OF  ROCKS.  [IX. 

TABLE    OF   THE   DENSITY   AND    POROSITY    OP   VARIOUS   ROCKS. 


' 

I. 

II. 

III. 

IV. 

1 

Sandstone,  Potsdam,  —  hard  and  white 

2.607 

2.644 

1.39 

0.50 

2 

Sandstone,  Potsdam,  —  hard  and  white 

2.560 

2.638 

2.72 

1.06 

3 

Sandstone,  Potsdam,  —  hard  and  white 

2.563 

2.633 

2.26 

0.88 

4 

Sandstone,  Potsdam,  —  hard  and  white 

2.557 

2.618 

2.47 

0.96 

5 

Sandstone,  Potsdam,  with  Scolithus  . 

2.453 

2.636 

6.94 

2.83 

6 

Sandstone,  Potsdam  

2.432 

2.641 

7.90 

3.25 

7 

Sandstone,  Potsdam,  with  Lingula     . 

2.366 

2!  611 

9.35 

3.96 

8 

Sandstone,  Sillery,  —  green,  argillaceous 

2.719 

2.795 

2.73 

1.00 

9 

Sandstone,  Sillery,  —  green,  argillaceous 

2.642 

2.719 

2.85 

1.08 

10 

Sandstone,  Medina,  —  red,  argillaceous 

2.529 

2.767 

8.37 

3.31 

11 

Sandstone,  Medina,  —  red,  argillaceous 

2.481 

2.776 

10.06 

4.04 

12 

Sandstone,  Devonian,  —  fine,  gray     . 

2.110 

2.646 

20.24 

9.59 

13 

Sandstone,  Devonian,  —  fine,  gray    . 

2.099 

2.645 

20.62 

9.85 

14 

Sandstone,  Devonian,  —  fine,  gray    . 

2.086 

2.649 

21.27 

10.22 

15 

Shale,  Sillery,  —  red,  argillaceous      . 

2.674 

2.784 

3.96 

1.49 

16 

Shale,  Hudson  River,  —  black,  argil'ous 

2.529 

2.747 

7.94 

3.14 

17 

Shale,  Utica,  —  pyroschist  .... 

2.317 

2.334 

0.75 

0.32 

18 

Shale,  Utica,  —  pyroschist  .... 

2.373 

2.396 

0.93 

0.39 

19 

Shale,  Utica,  —  pyroschist  .... 

2.370 

2.421 

2.10 

0.88 

20 

Limestone,  Trenton,  —  black,  compact 

2.706 

2.714 

0.30 

0.11 

21 

Limestone,  Trenton,  —  gray,  compact 

2.707 

2.715 

0.32 

0.11 

22 

Limestone,  Trenton,  —  gray,  crystalline 

2.643 

2.673 

1.16 

0.44 

23 

Limestone,  Trenton,  —  gray,  crystalline 

2.671 

2.708 

1.34 

0.50 

24 

Limestone,  Trenton,  —  gray,  crystalline 

2.638 

2.684 

1.70 

0.65 

25 

Dolomite,  Niagara,  —  gray,  crystalline 

2.537 

2.679 

5.27 

2.08 

26 

Dolomite    Calciferous 

2.772 

2.833 

2.15 

0.78 

27 

Dolomite    Calciferous     

2.737 

2.838 

3.53 

1.28 

28 

Dolomite    Calciferous 

2.635 

2.822 

6.61 

2.51 

29 

Dolomite    Calciferous      

2.601 

2.832 

7.22 

2.77 

30 

2.527 

2.829 

10.60 

4.19 

31 

Dolomite    Guelph            

2.528 

2.810 

10.04 

3.97 

32 

2.517 

2.825 

10.92 

4.33 

33 

Dolomite,  Chazy,  argillaceous  .     .     . 

2.442 

2.824 

13.55 

5.55 

34 

Dolomite,  Chazy,  argillaceous  .     .     . 

2.717 

2.823 

3.75 

1.39 

35 

Dolomite,  Chazy,  argillaceous  .     .     . 

2.693 

2.825 

4.69 

1.73 

36 

Dolomite,  Chazy,  argillaceous  .     .     . 

2.598 

2.891 

10.12 

3.89 

37 

Limestone,  Tertiary  (Caen,  France)    . 

1.859 

2.637 

29.49 

15.85 

38 

Limestone,  Tertiary  (Caen,  France)   . 

1.860 

2.644 

26.93 

14.48 

39 

Limestone,  Tertiary  (Caen,  France)   . 

1.839 

2.611 

29.54 

16.05 

reference  to  the  choice  of  building-stones  for  the  Houses  of  Parliament. 
They  made  use  of  blocks  of  an  inch  cube,  which  were  first  soaked  in  water 
and  then  placed  under  the  vacuum  of  an  air-pump,  as  in  my  own  experi- 
ments. The  following  examples  are  taken  from  a  table  in  the  above  re- 
port, giving  the  results  for  thirty-six  specimens  of  building-stones.  The 
value  of  x  in  III.,  or  the  absorption  of  water  for  100  volumes  of  rock,  as 
determined  by  them,  is  as  follows  :  For  three  silicious  limestones,  5.3,  8.5, 


IX.]  POROSITY  OF  BOCKS.  167 

The  rocks  in  the  preceding  table,  with  the  exception  of  six,  are 
from  the  palaeozoic  formations  of  Canada,  including,  as  will  be  seen, 
pure  limestones  of  the  Trenton  formation,  dolomiies  of  the  Calcner- 
ous  sand-rock,  the  Chazy,  the  Onondaga  (or  Saliiia),  the  Niagara,  and 
the  Guelph,  a  local  formation  resting  upon  the  Niagara.  The  sand- 
stones are  from  the  Potsdam,  the  Medina,  and  the  Sillery,  a  mem- 
ber of  the  Quebec  group,  which  is  associated  with  the  argillaceous 
shale  No.  15,  with  which  are  compared  the  argillaceous  shale  of  the 
Hudson  River  group  and  the  compact  pyroschists  of  the  Utica 
formation.  I  have  given  in  Nos.  12, 13,  and  14  determinations  with 
three  specimens  of  a  fine  gray  and  very  porous  sandstone  from 
Ohio,  of  Devonian  or  Lower  Carboniferous  age,  and  much  used  for 
building.  Nos.  37,  38,  and  39  are  three  specimens  of  the  well-known 
soft  limestone  of  Caen,  in  France,  so  much  employed  in  that  country 
for  architectural  purposes. 

10.9;  for  four  nearly  pure  limestones  from  the  oolite,  18.0,  20.6,  24.4,  31.0; 
for  four  magnesian  limestones,  18.2,  23.9,  24.9,  26.7;  and  for  six  sand- 
stones, 10.7,  11.2,  14.3,  15.6,  17.4,  and  22.1.  These  numbers  represent 
the  absorption  obtained  by  the  aid  of  the  air-pump,  without  which  it  is 
impossible  to  remove  all  the  air  from  the  pores  of  the  previously  dried 
rock.  Thus  a  cube  of  two  inches  of  a  sandstone  which  takes  up  in  this 
way  14.3  of  water  only  absorbed  8.0  by  prolonged  immersion  in  water;  an 
oolitic  limestone,  capable  of  holding  20.6,  in  like  manner  absorbed  only 
13.5  ;  and  a  magnesian  limestone  only  9.1,  instead  of  24.4.  (See,  also,  On  the 
Porosity  of  Rocks,  Delesse,  Bull.  Soc.  Geol.  de  France  (2),  XIX.  64.) 


X. 


ON  PETROLEUM,  ASPHALT,  PYRO- 
SCHISTS,  AND  COAL. 

In  the  following  paper  on  the  Oil-bearing  Limestone  of  Chicago,  read  before  the 
American  Association  for  the  Advancement  of  Science,  in  1870,  and  published  in  the 
American  Journal  of  Science  for  June,  1871,  will  be  found  a  summary  of  my  conclu- 
sions on  the  geological  history  of  petroleum.  To  it  are  appended  extracts  from  an 
earlier  paper  in  the  same  Journal  for  March,  1863,  On  Bitumens  and  Pyroschists,  and 
some  later  observations  by  Dawson  and  myself  on  the  vegetable  tissues  forming  coal. 
The  reader  is  also  referred  in  connection  with  petroleum  to  my  paper  on  the  Geology 
of  Southwestern  Ontario,  in  the  same  Journal  for  November,  1868,  and  to  Notes 
on  the  Oil- Wells  of  Terre  Haute,  Indiana,  iu  that  for  November,  1871. 

WHEN,  in  1861,*  I  first  published  my  views  on  the  petro- 
leum of  the  great  American  palaeozoic  basin,  I.  expressed  the 
opinion  that  the  true  source  of  it  was  to  be  looked  for  in  cer- 
tain limestone  formations  which  had  long  been  known  to  be 
oleiferous.  I  referred  to  the  early  observations  of  Eaton  and 
Hall  on  the  petroleum  of  the  Niagara  limestone,  to  numerous 
instances  of  the  occurrence  of  this  substance  in  the  Trenton 
and  Corniferous  formations,  and,  in  Gaspe",  in  limestones  of 
Lower  Helderberg  age.  Subsequently,  in  this  Journal  for 
March,  1863,  and  in  the  Geology  of  Canada,  I  insisted  still 
further  upon  the  oleiferous  character  of  the  Corniferous  lime- 
stone in  southwestern  Ontario,  which  appears  to  be  the  source 
of  the  petroleum  found  in  that  region.  I  may  here  be  permit- 
ted to  recapitulate  some  of  my  reasons  for  concluding  that 
petroleum  is  indigenous  to  these  limestones,  and  for  rejecting 
the  contrary  opinion,  held  by  some  geologists,  that  its  occur- 
rence in  them  is  due  to  infiltration,  and  that  its  origin  is  to  be 
sought  in  an  unexplained  process  of  distillation  from  pyro- 
schists  or  so-called  bituminous  shales.  These  occur  at  three 
*  See  the  Appendix  to  this  paper. 


X.]  THE  OIL-BEARING  LIMESTONE  OF  CHICAGO.        169 

distinct  horizons  in  the  New  York  system,  and  are  known  as 
the  Utica  slate,  immediately  above  the  Trenton  limestone,  and 
the  Marcellns  and  Genesee  slates  which  lie  above  and  below 
the  Hamilton  shales ;  the  latter  being  separated  from  the  un- 
derlying Corniferous  limestone  by  the  Marcellus  state. 

First,  these  various  pyroschists  do  not,  except  in  rare  in- 
stances, contain  any  petroleum  or  other  form  of  bitumen. 
Their  capability  of  yielding  volatile  liquid  hydrocarbons  of 
pyrogenous  oils,  allied  in  composition  to  petroleum,  by  what  is 
known  to  chemists  as  destructive  distillation,  at  elevated  tem- 
peratures, is  a  property  which  they  possess  in  common  with 
wood,  peat,  lignite,  coal,  and  most  substances  of  organic  origin, 
and  has  led  to  their  being  called  bituminous,  although  they  are 
not  in  any  proper  sense  bituminiferous.  The  distinction  is  one 
which  will  at  once  be  obvious  to  all  those  who  are  familiar 
with  chemistry,  and  who  know  that  pyroschists  are  argilla- 
ceous rocks  containing  in  a  state  of  admixture  a  brownish 
insoluble  and  infusible  hydrocarbonaceous  matter,  allied  to  lig- 
nite or  to  coal. 

Second,  the  pyroschists  of  these  different  formations  do  not, 
so  far  as  known,  in  any  part  of  their  geological  distribution, 
whether  exposed  at  the  surface  or  brought  up  by  borings  from 
depths  of  many  hundred  feet,  present  any  evidence  of  having 
been  submitted  to  the  temperature  required  for  the  generation 
of  volatile  hydrocarbons.  On  the  contrary,  they  still  retain  the 
property  of  yielding  such  products  when  exposed  to  a  sufficient 
heat,  at  the  same  time  undergoing  a  charring  process  by  which 
their  brown  color  is  changed  to  black.  In  other  words,  these 
pyroschists  have  not  yet  undergone  the  process  of  destructive 
distillation. 

Third,  the  conditions  in  which  the  oil  occurs  in  the  lime- 
stones are  inconsistent  with  the  notion  that  it  has  been  intro- 
duced into  these  rocks  by  distillation.  The  only  probable  or 
conceivable  source  of  heat,  in  the  circumstances,  being  from 
beneath,  the  process  of  distillation  would  naturally  be  one  of 
ascension,  the  more  so  as  the  pores  of  the  underlying  strata 
would  be  filled  with  water.  Such  being  the  case,  the  petro- 

8 


170  THE   OIL-BEARING  LIMESTONE   OF   CHICAGO.  [X. 

leum  of  the  Silurian  and  Lower  Devonian  limestones  must 
have  been  derived  from  the  Utica  slate  beneath.  This  rock, 
however,  is  unaltered,  and  moreover,  the  intermediate  sand- 
stones and  shales  of  the  Loraine,  Medina,  and  Clinton  forma- 
tions are  destitute  of  petroleum,  which  must,  on  this  hypothe- 
sis, have  passed  through  all  these  strata  to  condense  in  the 
Niagara  and  Corniferous  limestones.  More  than  this,  the 
Trenton  limestone,  which,  on  Lake  Huron  and  elsewhere,  has 
yielded  considerable  quantities  of  petroleum,  has  no  pyroschists 
beneath  it,  but  on  Lake  Huron  rests  on  ancient,  crystalline 
rocks,  with  the  intervention  only  of  a  sandstone  devoid  of 
organic  or  carbonaceous  matter.  The  rock-formations  holding 
petroleum  are  not  only  separated  from  each  other  by  great 
thicknesses  of  porous  strata  destitute  of  it,  but  the  distribution 
of  this  substance  is  still  further  localized,  as  I  many  years  since 
pointed  out.  The  petroleum  is,  in  fact,  in  many  cases,  confined 
to  certain  bands  or  layers  in  the  limestone,  in  which  it  fills  the 
pores  and  the  cavities  of  fossil  shells  and  corals,  while  other 
portions  of  the  limestone,  above,  below,  and  in  the  prolon- 
gation of  the  same  stratum,  although  equally  porous,  contain 
no  petroleum.  From  all  these  facts  the  only  reasonable  con- 
clusion seems  to  me  to  be  that  the  petroleum,  or  rather  the 
materials  from  which  it  has  been  formed,  existed  in  these  lime- 
stone rocks  from  the  time  of  their  first  deposition.  The  view 
which  I  put  forward  in  1861,  that  petroleum  and  similar  bitu- 
mens have  resulted  from  a  peculiar  "  transformation  of  vegeta- 
ble matters,  or  in  some  cases  of  animal  tissues  analogous  to 
these  in  composition,"  has  received  additional  support  from  the 
observations  of  Lesley*  in  West  Virginia  and  Kentucky,  and 
.from  .the  more  recent  ones  of  Peckham.t 

The  objections  to  this  view  of  the  origin  and  geological  rela- 
tions of  petroleum  have  been  for  the  most  part  founded  on 
incorrect  notions  of  the  geological  structure  of  southwestern 
Ontario,  which  has  afforded  me  peculiar  facilities  for  studying 

*  Rep.  Geol.  Canada,  1866,  240  ;  and  Proc.  Amer.  Philos.  Soc.,  X.  33, 
187. 
$  Ibid.,  X.  445. 


X.]  THE   OIL-BEARING  LIMESTONE  OF  CHICAGO.          171 

the  question.  In  this  region,  it  has  been  maintained  by  Win- 
chell  that  the  source  of  the  petroleum  is  to  be  sought  in  the 
Devonian  pyroschists.  I  however  showed  in  1866,  as  the  re- 
sult of  careful  studies  of  the  various  borings  :  first,  that  none 
of  the  oil-wells  were  sunk  in  the  Genesee  slates,  but  along 
denuded  anticlinals,  where  these  rocks  have  disappeared,  and 
where,  except  the  thin  layer  of  Marcellus  slate  sometimes  met 
with  at  the  base  of  the  Hamilton  shales,  no  pyroschists  are 
found  above  the  Trenton  limestone.  Second,  that  the  reser- 
voirs of  petroleum  in  the  wells  sunk  into  the  Hamilton  shales 
are  sometimes  met  with  in  this  formation,  and  sometimes,  in 
adjacent  borings,  only  in  the  underlying  Corniferous.  Exam- 
ples of  this  have  been  cited  by  me  in  wells  in  Enniskillen, 
Bothwell,  Chatham,  and  Thamesville,  where  petroleum  was 
only  found  at  depths  of  from  thirty  to  one  hundred  and  twenty 
feet  in  the  Corniferous  limestone,  in  all  of  these  places  over- 
laid by  the  Hamilton  shales.  It  was  also  shown,  that  in  two 
localities  in  this  region,  namely,  at  Tilsonburg  and  in  Maid- 
stone,  where  the  Corniferous  is  covered  only  by  post-pliocene 
clays,  petroleum  in  considerable  quantities  has  been  obtained 
by  sinking  into  the  limestone.*  That  the  supplies  of  petro- 
leum in  such  localities  are  less  abundant  than  in  parts  where  a 
mass  of  shales  and  sandstones  overlies  the  oil-bearing  limestone, 
is  explained  by  the  fact  that  both  the  pores  and  the  fissures  in 
the  superior  strata  serve  to  retain  the  oil,  in  a  manner  analo- 
gous to  the  post-pliocene  gravels  in  some  parts  of  this  region, 
which  are  the  sources  of  the  so-called  surface  oil-wells.  It  is, 
therefore,  not  surprising  that  examples  of  pyroschists  impreg- 
nated with  oil  should  sometimes  occur,  but  the  evidence  of  the 
existence  of  indigenous  petroleum,  which  is  so  clear  in  the 
various  limestones,  is  wanting  in  the  case  of  the  pyroschists ; 
although  concretions  holding  petroleum,  have  been  observed  in 
the  Marcellus  and  the  Genesee  slates  of  New  York.  There  is, 
however,  reason  to  believe,  as  I  have  elsewhere  pointed  out, 
that  much  of  the  petroleum  of  Pennsylvania,  Ohio,  and  the 

*  American  Journal  of  Science  (2),  XL VI.  360  ;  and  Report  Geol.  Canada, 
1866,  pp.  241  -  250. 


172  THE   OIL-BEARING  LIMESTONE  OF   CHICAGO.  [X. 

adjacent  regions  is  indigenous  to  certain  sandstone  strata  in 
the  Devonian  and  Carboniferous  rocks.* 

At  the  meeting  of  the  American  Association  for  the  Ad- 
vancement of  Science  at  Chicago,  in  August,  1868,  in  a  dis- 
cussion which  followed  the  reading  of  a  paper  by  myself  on 
the  Geology  of  Ontario,t  it  was  contended  that,  although  the 
various  limestones  which  have  been  mentioned  are  truly  oleifer- 
ous,  the  quantity  of  petroleum  which  they  contain  is  too  incon- 
siderable to  account  for  the  great  supplies  furnished  by  oil-pro- 
ducing districts,  like  that  of  Ontario,  for  example.  This  opinion 
being  contrary  to  that  which  I  had  always  entertained,  I  re- 
solved to  submit  to  examination  the  well-known  oil-bearing 
limestone  of  Chicago. 

This  limestone,  the  quarries  of  which  are  in  the  immediate 
vicinity  of  the  city,  is  filled  with  petroleum,  so  that  blocks  of  it 
which  have  been  used  in  buildings  are  discolored  by  the  exuda- 
tion of  this  substance,  which,  mingled  with  dust,  forms  a  tarry 
coating  upon  the  exposed  surfaces.  The  thickness  of  the  oil- 
bearing  beds,  which  are  massive  and  horizontal,  is,  according 
to  Professor  Worthen,  from  thirty-five  to  forty  feet,  and  they 
occupy  a  position  about  midway  in  the  Niagara  formation, 
which  has  in  this  region  a  thickness  of  from  200  to  250  feet. 
As  exposed  in  the  quarry,  the  whole  rock  seems  pretty  uniformly 
saturated  with  petroleum,  which  exudes  from  the  natural  joints 
and  the  fractured  surfaces,  and  covers  small  pools  of  water  in 
the  depressions  of  the  quarry.  I  selected  numerous  specimens 
of  the  rocks  from  different  points  and  at  various  levels,  with  a 
view  of  getting  an  average  sample,  although  it  was  evident  that 
they  had  already  lost  a  portion  of  their  original  content  of 
petroleum.  After  lying  for  more  than  a  year  in  my  laboratory 
they  were  submitted  to  chemical  examination.  The  rock, 
though  porous  and  discolored  by  petroleum,  is,  when  freed 
from  this  substance,  a  nearly  white,  granular,  crystalline,  and 
very  pure  dolomite,  yielding  54.6  per  cent  of  carbonate  of  lime. 

Two  separate  portions,  each  made  up  of  fragments  obtained 

*  Report  Geol.  Canada,  1866,  p.  240. 

t  American  Journal  of  Science  (2),  XL VI.  355. 


X.]  THE  OIL-BEARING  LIMESTONE  OF  CHICAGO.          173 

by  breaking  up  some  pounds  of  the  specimens  above  mentioned, 
and  supposed  to  represent  an  average  of  the  rock  exposed  in 
the  quarry,  were  reduced  to  coarse  powder  in  an  iron  mortar. 
Of  these  two  portions,  respectively,  100  and  138  grammes  were 
dissolved  in  warm  dilute  hydrochloric  acid.  The  tarry  residue 
which  remained  in  each  case  was  carefully  collected  and  treated 
with  ether,  in  which  it  was  readily  soluble  with  the  exception 
of  a  small  residue.  This,  in  one  of  the  samples,  was  found 
equal  to  .40  per  cent,  of  which  .13  was  volatilized  by  heat  with 
the  production  of  a  combustible  vapor  having  a  fatty  odor; 
the  remainder  was  silicious.  The  brown  ethereal  solutions  were 
evaporated,  and  the  residuum,  freed  from  water  and  dried  at 
100°  C.,  weighed,  in  the  two  experiments,  equal  to  1.570  and 
1.505  per  cent  of  the  rock,  or  a  mean  of  1.537.  It  was  a  viscid 
reddish-brown  oil,  which,  though  deprived  of  its  more  volatile 
portions,  still  retained  somewhat  of  the  odor  of  petroleum 
which  is  so  marked  in  the  rock.  Its  specific  gravity,  as  deter- 
mined by  that  of  a  mixture  of  alcohol  and  water  in  which  the 
globules  of  the  petroleum  remained  suspended,  was  .935  at 
16°  C.  Estimating  the  density  of  the  somewhat  porous  dolo- 
mite at  2.6,  we  have  the  proportion  .935:2.600::1.537:4.260; 
so  that  the  volume  of  the  petroleum  obtained  equalled  4.26  per 
cent  of  the  rock.  This  result  is  evidently  too  low,  for  two  rea- 
sons :  first,  because  the  rock  had  already  lost  a  part  of  its  oil, 
while  in  the  quarry  and  subsequently,  before  its  examination ; 
and  secondly,  because  the  more  volatile  portions  had  been 
dissipated  in  the  process  of  extraction  just  described. 

In  assuming  100.00  parts  of  the  rock  to  hold  4.25  parts  by 
volume  of  petroleum,  we  are  thus  below  the  truth  in  the  follow- 
ing calculations.  A  layer  of  this  oleiferous  dolomite  one  mile 
(5,280  feet)  square  and  one  foot  in  thickness  will  contain 
1,184,832  cubic  feet  of  petroleum,  equal  to  8,850,069  gallons 
of  231  cubic  inches,  and  to  221,247  barrels  of  forty  gallons 
each.  Taking  the  minimum  thickness  of  thirty-five  feet,  as- 
signed by  Mr.  "Worthen  to  the  oil-bearing  rock  at  Chicago,  we 
shall  have  in  each  square  mile  of  it  7,743,745  barrels,  or  in 
round  numbers  seven  and  three  quarter  millions  of  barrels  of 


174          THE  OIL-BE ATtftfG  LIMESTONE  OF  CHICAGO.  [X. 

petroleum.  The  total  produce  of  the  great  Pennsylvania  oil- 
region  for  the  ten  years  from  1860  to  1870  is  estimated  at 
twenty-eight  millions  of  barrels  of  petroleum,  or  less  than 
would  be  contained  in  four  square  miles  of  the  oil-bearing 
limestone  formation  of  Chicago. 

It  is  not  here  the  place  to  insist  upon  the  geological  condi- 
tions which  favor  the  liberation  of  a  portion  of  the  oil  from  such 
rocks,  and  its  accumulation  in  fissures  along  certain  anticlinal 
lines  in  the  broken  and  uplifted  strata.  These  points  in  the 
geological  history  of  petroleum  were  shown  by  me  in  my  first 
publications  on  the  subject  in  March  and  July,  1861,  referred 
to  on  the  next  page,  and  independently,  about  the  same  time, 
•by  Professor  E.  B.  Andrews  in  this  Journal  for  July,  1861.* 

The  proportion  of  petroleum  in  the  rock  of  Chicago  may  be 
exceptionally  large,  but  the  oleiferous  character  of  great  thick- 
ness of  rock  in  other  regions  is  well  established,  and  it  will 
be  seen  from  the  above  calculations  that  a  very  small  propor- 
tion of  the  oil  thus  distributed  would,  when  accumulated  along 
lines  of  uplift  in  the  strata,  be  more  than  adequate  to  the  sup- 
ply of  all  the  petroleum  wells  known  in  the  regions  where 
these  oil-bearing  rocks  are  found.  With  such  sources  exist- 
ing ready  formed  in  the  earth's  crust,  it  seems  to  me,  to  say  the 
least,  unphilosophical  to  search  elsewhere  for  the  origin  of 
petroleum,  and  to  imagine  it  to  be  derived  by  some  unex- 
plained process  from  rocks  which  are  destitute  of  the  sub- 
stance. 

*  American  Journal  of  Science  (2),  XXXII.  85.  See  also  papers  on  the 
subject  by  Andrews  and  by  Professor  Evans,  Ibid.  (2),  XL.  33,  334  ;  and  one 
by  the  author  (2),  XXXV.  170  ;  also  Keport  Geological  Survey  of  Canada, 
1866,  pp.  256,  257. 


X.]  BITUMENS  AND  PYROSCHISTS.  175 


APPENDIX. 

ON   BITUMENS   AND   PYROSCHISTS. 

(1861-1863.) 

This  paper  is  reprinted  from  the  American  Journal  of  Science  for  March,  1863,  but 
many  of  the  facts  and  deductions  which  it  contains  appeared  in  an  earlier  paper, 
entitled  Notes  on  the  History  of  Petroleum,  in  the  Canadian  Naturalist  for  July,  1861, 
reprinted  in  the  Chemical  News,  and  also  in  the  Report  of  the  Smithonian  Institution 
for  1862.  I  had  for  some  time  previously  maintained  that  the  source  of  the  petroleum 
of  the  West  was  not,  as  was  generally  thought,  to  be  found  in  the  Devonian  pyro- 
schists,  but  in  the  underlying  fossiliferous  limestones,  and  had  shown  the  relation  of 
the  oil-springs  to  anticlinals.—  See  a  report  of  my  lecture  before  the  Board  of  Arts  of 
Lower  Canada,  in  the  Montreal  Gazette  of  March  1,  1861. 

IT  is  proposed  in  the  following  pages  to  bring  together  some  facts 
and  theoretical  considerations  bearing  upon  the  nature,  origin,  and 
distribution  of  bitumens,  together  with  a  few  remarks  on  the  rocks 
commonly  called  bituminous  shales.  Under  the  general  name  of 
bitumen,  as  is  well  known,  are  included  both  the  liquid  forms, 
petroleum  and  naphtha,  and  the  solid  varieties  known  as  asphalt  or 
mineral  pitch.  The  related  substances  guayaquillite  and  berenge- 
lite,  and  the  substance  known  as  idrialine,  seem  from  the  modes  of 
their  occurrence  to  have  a  similar  origin  to  asphalt,  and  thus  to  be 
distinct  from  fossil  resins.  The  characters  of  fusibility  and  solu- 
bility in  liquids  like  benzole  and  sulphuret  of  carbon,  serve  to  dis- 
tinguish the  solid  bitumens  from  coal  and  some  other  matters  about 
to  be  noticed.  It  is  to  be  remarked  that  the  chemical  composition 
of  these  bodies  varies  considerably  ;  the  earlier  analyses  of  petro- 
leum and  naphtha  give  a  composition  which  approaches  CnHH  ;  but 
the  later  investigations  of  De  la  Rue  and  Muller  on  the  products 
distilled  from  the  petroleum  of  Rangoon,  and  those  of  Uelsmann  on 
that  from  Sehnde,  show  a  slight  excess  of  hydrogen,  the  various 
hydrocarbons  having,  for  the  most  part,  the  formula  C^Hn+j.  The 
first  formula  Cnl{n  may  however  be  adopted,  as  expressing  approxi- 
matively  the  composition  of  the  liquid  bitumens.  The  different 
analyses  of  asphalt  show  a  diminished  quantity  of  hydrogen,  and 
small  quantities  of  oxygen.  Thus  the  elastic  bitumen  from  Der- 
byshire gave  to  Johnston  results  which  may  be  represented  by 
;  *  of  two  varieties  of  asphalt  analyzed  by  Ebelmann,  the 


*  In  these  formulas,  which  have  been  calculated  for  twenty-four  equivalents 
of  carbon,  to  compare  with  cellulose,  C^H^O,,,  I  have  designed  to  represent 


176  '-BITUMENS  AND   PYROSCHISTS.  [X. 

one  from  Bastennes  gave  C24H160OT,  while  that  from  near  Naples 
may  be  represented  by  C24HU.6O2,  and  an  asphalt  from  Mexico  gave 
to  Regnault  C2tH17O2.  The  analyses  of  Johnston  shows  that  guaya- 
quillite  and  berengelite  do  not  differ  greatly  from  these  in  the  pro- 
portions of  carbon  and  hydrogen.  Passing  from  the  asphalts  to 
idrialine,  the  results  of  whose  analysis  are  represented  by  C24H8,  we 
have  a  hydrocarbon  with  a  minimum  of  hydrogen.  It  is  well  in 
this  place  to  compare  the  above  results  with  the  formula  C^H^O^ , 
which  is  deduced  from  Wetherell's  analysis  of  the  so-called  albertite 
or  Albert  coal.  A  "lignite  passing  into  mineral  resin"  gave  to 
Regnault  C24H1503.3,  and  five  analyses  of  bituminous  coal  by  the 
same  chemist  yield  from  C24H800.9  to  C24H1003.3,  while  the  mean 
composition  deduced  by  Johnston  from  several  analyses  of  coal  was 
C24H9,  with  from  O2  to  04.  From  these  results  it  will  be  seen  that 
some  asphalts  approach  bituminous  coals  in  composition.  That  of 
Naples,  which  is  completely  fusible  at  140°  C.,  contains  less  hydro- 
gen and  more  oxygen  than  the  albertite,  while  the  idrialine  is  near 
in  composition  to  certain  bituminous  coals,  which  are  thus  almost 
isomeric  with  some  fusible  bitumens  ;  so  that  it  is  easy  to  conceive 
the  same  organic  matters  giving  rise  either  to  coal  or  to  asphalt, 
even  without  losing  their  structure.  Such  appears  to  be  the  case  in 
the  tertiary  strata  of  Trinidad  and  Venezuela,  the  bitumen  of  which, 
from  Mr.  Wall's  researches,  seems  to  have  arisen  from  "  a  special 
mineralization  of  vegetable  remains  in  certain  strata,  which  has 
resulted  in  the  production  of  bitumen,  instead  of  coal  or  lignite." 
This  conversion,  according  to  him,  "is  not  attributable  to  heat, 
nor  of  the  nature  of  a  distillation,  but  is  due  to  chemical  reactions 
at  the  ordinary  temperature,  and  under  the  normal  conditions  of 
climate."  Mr.  Wall  also  describes  portions  of  wood  from  these 
deposits,  which  have  been  partially  converted  into  bitumen,  and 

simply  the  results  of  analysis,  withcmt  attempting  to  fix  the  constitution  of 
the  matters  in  question. 

In  the  notation  employed,  H  =  1,  C  =  6,  and  0  =  8.  As  it  is  not  generally 
used  in  the  American  Journal  of  Science,  I  have  not  thought  necessary  to 
adopt,  in  this  paper,  the  double  equivalent  of  the  latter  elements,  now  em- 
ployed by  so  many  chemists.  I  may,  however,  call  attention  to  the  fact  that 
I  was,  I  believe,  the  first  to  propose  such  a  change,  when,  in  1853,  I  asserted 
that  the  even  coefficients  of  oxygen,  sulphur,  and  carbon,  in  ordinary  for- 
mulas seem  to  furnish  a  conclusive  reason  for  doubling  their  equivalents,  or 
for  dividing  those  of  hydrogen,  chlorine,  nitrogen,  and  the  metals,  according 
as  four  volumes  or  two  -volumes  are  taken  as  the  equivalent.  (Theory  of 
Chemical  Changes,  Am.  Jour,  of  Science  (2),  XV.  p.  230.  [Reprinted  as 
Essay  XVI.  of  the  present  volume.]) 


X.]  BITUMENS  AND  PYROSCHISTS.  177 

leave,  when  this  is  removed  by  solvents,  a  residue  of  woody  tissue. 
(Proc.  Geol.  Soc.  London,  May,  1860.)  These  observations  have 
been  confirmed  by  an  eminent  microscopist  and  chemist,  whose 
results,  lately  communicated  to  me  by 'himself,  are  not  yet  pub- 
lished. 

The  chemical  changes  by  which  the  conversion  of  woody  tissue 
into  peat,  lignite  and  bituminous  coal  is  effected,  are  too  well  known 
to  be  repeated  here.  The  abstraction  of  variable  proportions  of 
water,  carbonic  acid,  and  marsh-gas  may  give  rise  either  to  hydro- 
carbons like  C^Hg,  which  represents  idrialine  and  the  basis  of  most 
bituminous  coals,  to  CS4HW,  which  is  the  approximate  formula  of 
the  hydrocarbons  of  many  asphalts,  or  to  C^H^,  which  represents 
petroleum.  The  removal  of  further  amounts  of  marsh-gas,  C2H4, 
may  even  convert  bituminous  coal  into  anthracite,  as  Bischof  has 
pointed  out ;  and  we  conceive  that  although  heat  has  in  many  cases 
given  rise  to  this  conversion,  by  a  subterranean  coking,  the  change 
may  often  have  been  the  result  of  decompositions  going  on  at 
ordinary  temperatures.  Anthracite  or  nearly  pure  carbon,  on  the 
one  hand,  and  petroleum  or  carbon  with  a  maximum  of  hydrogen, 
on  the  other,  represent  the  two  extremes  of  a  series  of  which  bitu- 
minous coals  and  asphalts  are  intermediate  terms. 

Petroleum,  as  is  well  known,  impregnates  certain  rocks,  from 
which  it  flows  spontaneously,  and  the  solid  forms  of  bitumen  are 
often  disseminated  throughout  limestones  or  sandstones,  from  which 
they  may  be  in  part  removed  by  heat,  and  more  completely  by  sol- 
vents such  as  benzole.  To  such  rocks  the  term  "  bituminous"  may 
be  correctly  applied,  but  it  is  often  inappropriately  given  to  sub- 
stances like  coal  and  certain  combustible  schists,  which  contain 
little  or  no  bitumen,  but  yield,  by  destructive  distillation,  volatile 
hydrocarbons,  more  or  less  resembling  those  obtained  from  asphalt 
or  petroleum.  Analogous  products  are,  however,  obtained  by  the 
distillation  of  lignite,  peat,  and  even  of  wood,  so  that  the  epi- 
thet "  bituminous,"  applied  to  hydrogenous  coals  and  combustible 
schists,  raises  a  false  distinction,  and  perpetuates  an  error.  I 
therefore  proposed  some  time  since  to  distinguish  these  so-called 
bituminous  schists,  the  brandschiefer  of  the  Germans,  by  the  name 
of  pyroschists.  This  is  the  equivalent  of  the  German  term,  and  has 
a  precedent  in  the  name  of  pyrorthite,  given  by  Berzelius  to  a  sub- 
stance which  appears  to  be  a  mixture  of  orthite  with  a  combustible 
hydrocarbonaceous  matter.  Pyroschists  are  well  known  to  occur 
in  almost  every  geological  group  from  the  Cambrian  to  the  tertiary, 
8*  L 


178  BITUMENS  AND   PYROSCHISTS.  [X. 

and  are  often,  like  coal,  employed  as  valuable  sources  of  volatile 
hydrocarbons,  although  like  it  they  contain  little  or  no  bitumen. 
They  may  be  regarded  as  clays  or  marls,  holding,  in  a  state  of  in- 
timate admixture,  a  variable  proportion  of  a  matter  approaching  to 
coal  in  its  chemical  characters.  Although  frequently  dark  brown  or 
black  in  color,  they  are  sometimes  light  brown  or  even  yellowish- 
gray,  as  is  the  case  with  the  Jurassic  pyroschists  of  the  department 
of  the  Doubs,  and  those  of  tertiary  age  near  Clermont,  both  in  France. 
Remarkable  examples  of  this  are  also  given  by  Professor  J.  D. 
Whitney  in  the  pyroschists  from  the  Utica  formation  in  Iowa, 
which  were  yellowish-brown,  weathering  to  a  bluish-ash  color. 
They,  however,  blackened  when  exposed  to  he'at,  burning  with  a 
bright  flame,  and  contained  from  eleven  to  twenty  per  cent  of  com- 
bustible matter.*  ....  A  pyroschist  of  the  Utica  formation,  from 
Collingwood  on  Lake  Huron,  examined  by  me,  gave  to  dilute  hydro- 
chloric acid  from  fifty-three  to  fifty-eight  per  cent  of  carbonate  of 
lime,  besides  a  little  magnesia  and  oxide  of  iron.  The  insoluble 
residue  was  snuff-brown  in  color,  and,  when  heated,  gave  off  a 
bituminous  odor.  When  ignited  in  a  close  vessel,  it  lost  1^.6  per 
cent  of  volatile  and  combustible  matters,  and  left  a  coal-black  resi- 
due, which,  by  calcination  in  the  open  air,  lost  8.4  per  cent  addi- 
tional, making  in  all  21.0  per  cent  of  volatile  and  carbonaceous 
matters,  and  left  an  ash-gray  argillaceous  residue.  This  schist, 
however,  contained  but  a  very  small  amount  of  bitumen  ;  for,  on 
treating  the  residue  from  a  dilute  acid  with  boiling  benzole,  there 
was  dissolved  about  1.0  per  cent  of  a  brown  bituminous  matter. 
The  residue,  when  heated,  no  longer  evolved  the  odor  of  bitumen, 
but  rather  one  like  burning  lignite,  and  still  gave,  by  ignition  in 
a  close  vessel,  11.8  per  cent  of  volatile  and  inflammable  matters. 
When  boiled  with  a  solution  of  caustic  soda,  this  was  scarcely  dis- 
colored. In  its  insolubility,  therefore,  the  organic  matter  of  this 
rock  resembles  true  coal  rather  than  lignite.  Attempts  have  been 
made,  on  a  large  scale,  to  distil  this  calcareous  schist  of  Colling- 
wood, which  was  found  to  yield  from  3.0  to  5.0  per  cent  of  oily 
and  tarry  matter,  besides  combustible  gases  and  water. 

Overlying  the  Hamilton  formation  in  Ontario  are  found  black 
pyroschists,  which  are  supposed  to  be  the  equivalent  of  the  Genesee 
slates  of  New  York.  A  specimen  of  these  from  Bosanquet  on  Lake 

*  For  numerous  analyses  of  pyroschists  from  this  geological  horizon, 
see  a  note  appended  to  this  paper  in  the  American  Journal  of  Science  (2), 
XXXV.  160. 


X.]  BITUMENS  AND   PYROSCHISTS.  179 

Huron  lost,  by  ignition  in  a  closed  vessel,  12.4  per  cent,  and  left  a 
black  residue,  which  was  not  calcareous.  A  portion  in  fine  powder 
was  digested  for  several  hours  with  heated  benzole,  which  took  up 
0.8  per  cent  of  brown  combustible  matter.  The  residue,  carefully 
dried  at  200°  F.,  then  lost,  by  ignition  in  a  close  vessel,  11.3  per  cent, 
and  by  subsequent  calcination  11.6  additional,  equal  to  23.7  per 
cent  of  combustible  and  volatile  elements.  The  calcined  residue 
was  gray  in  color.  By  distillation  in  an  iron  retort  there  were 
obtained  from  this  shale  4.2  per  cent  of  oily  hydrocarbons,  besides 
a  large  quantity  of  inflammable  gas,  and  a  portion  of  ammoniacal 
water. 

The  pyroschists  of  Bosanquet  belong  to  the  Devonian  series,  and 
contain  the  remains  of  land-plants,  so  that  a  partially  decayed  vege- 
tation may  be  supposed  to  have  been  the  source  of  the  organic 
matter  which  is  intimately  mingled  with  the  earthy  base  of  the  rock. 
Such  was  probably  the  case  in  the  abundant  pyroschists  of  the 
coal  period  ;  but  in  the  pyroschists  of  the  Utica  formation  (which 
are  Upper  Cambrian)  the  chief  organic  remains  to  be  detected  are 
graptolites,  with  a  few  brachiopods  and  crustaceans.  No  traces  .of 
terrestrial  vegetation  are  known  to  have  existed  at  that  time,  nor  do 
the  schists  contain  the  evidences  of  any  marine  plants.  The  pyro- 
schists of  mesozoic  age,  in  several  parts  of  Europe,  contain,  on  the 
contrary,  numerous  fossil  fishes,  from  the  soft  parts  of  which,  or 
other  animal  matters,  the  combustible  substance  of  these  rocks  is 
generally  supposed  to  be  derived.  (Dufrenoy,  Mineralogie,  IV.  p. 
603.)  Similar  questions  arise  with  regard  to  the  origin  of  the  bitu- 
mens of  the  various  geological  formations  already  noticed  ;  for  while 
in  some  cases,  as  in  the  tertiary  rocks  of  Trinidad,  they  are  clearly 
traced  to  a  vegetable  source,  bitumens  are  also  met  with  in  Cam- 
brian, Silurian,  and  Devonian  limestones  of  marine  origin,  which 
al>ound  in  shells  and  corals,  but  afford  no  traces  of  vegetable  remains. 
When,  however,  it  is  considered  that  the  lower  forms  of  animals 
contain  considerable  portions  of  a  non-azotized  tissue  analogous  in  its 
composition  to  that  of  plants,  and  that  even  muscular  tissue,  plus 
the  elements  of  water,  contains  the  elements  of  cellulose  and  ammo- 
nia, it  is  easy  to  understand  that  vegetable  and  animal  remains  may, 
by  their  slow  decomposition,  give  rise  to  similar  hydrocarbonaceous 
bodies.*  The  various  fermentations  of  which  sugar  is  susceptible 

*  This  relation  was  first  pointed  out  by  me  in  1849.  (American  Journal  of 
Science  (2),  VII.  p.  109.)  I  then  endeavored  to  show  that  the  albuminoid 
bodies  might  be  regarded  as  a  nitryl  of  cellulose,  or  some  isomeric  hydrate 
of  carbon,  and  represented  by  the  formula  C^HjjNjO,.  I  had  already  pro- 


180  ON   THE  OEIGIN   OF  COAL.  [X. 

suggest  analogies  to  the  different  transformations  of  organic  tissues 
which  have  resulted  in  the  formation  of  anthracite,  coal,  lignite, 
asphalt,  and  petroleum,  together  with  carbonic  acid  and  gaseous 
hydrocarbons  as  accessory  products.  (See  note  on  page  182.) 

[The  conclusions  of  the  remaining  nine  pages  of  the  ^bove  paper  are 
briefly  summed  up  in  the  preceding  one  on  The  Oil-bearing  Lime- 
stones of  Chicago.  As  a  supplement  to  the  remarks  on  the  origin 
of  coal  I  may  here  make  some  extracts  from  a  paper  on  Spore- 
Cases  in  Coal,  by  Dr.  J.  W.  Dawson,  in  the  American  Journal  of 
Science  for  April,  1871,  including  also  a  note  by  myself.  Dawson 
has  there  shown  that  while  some  exceptional  beds  of  coal  are  to  a 
large  extent  made  up  of  spores  and  spore-cases,  probably  of  lepido- 
dendron,  it  is  by  no  means  true  that  these  are,  as  some  have  con- 
jectured, the  principal  source  of  coal.  On  the  other  hand,  it  is  clear 

posed  to  regard  bone-gelatine  as  an  analogous  nitryl,  C24H2oN408 ;  which 
corresponds  to  one  equivalent  of  glucose  and  four  of  ammonia,  less  8  HO. 
These  nitryls,  it  was  conceived,  might,  under  certain  conditions,  regenerate 
ammonia  and  a  hydrate  of  carbon.  I  also  adduced  evidence  that  in  a  case  of 
diabetes,  sugar  was  generated  at  the  expense  of  ingested  gelatine.  (American 
Journal  of  Science  (2),  V.  p.  75;  VI.  p.  259;  and  Silliman's  Elements  of 
Chemistry,  p.  517. )  The  analyses  of  cartilage-gelatine,  or  chondrine,  in  like 
manner  correspond  very  nearly  to  a  nitryl  formed  from  Cz^^O^  (cane-sugar) 
and  three  equivalents  of  ammonia.  The  formula  thus  deduced,  C24Hi9N3Oio, 
requires  14.7  of  nitrogen. 

In  1856,  Dusart,  starting,  as  he  tells  us,  from  my  theoretical  views,  en- 
deavored to  produce  the  albuminoid  bodies  by  the  action  of  a  solution  of 
ammonia  on  starch,  lactose,  or  glucose  at  temperatures  of  150°  and  200°  C.  In 
this  way  he  obtained,  after  several  days,  an  azotized  body,  which  resembled 
gelatine.  It  was  precipitated  by  alcohol  in  elastic  filaments,  formed  an 
imputrescible  compound  with  tannin,  and,  when  heated,  gave  off  the  odor  of 
burning  horn.  Its  proportion  of  nitrogen  was  14.0  per  cent,  which  is  near 
that  of  chondrine.  (Comptes  Eendus  de  1* Academic,  May,  1861,  p.  974.) 
Schoonbroodt  has  since  asserted  the  possibility  of  converting  sugar  into  an 
albuminoid  substance,  and  reiterated  my  suggestion  that  the  albuminoids  are 
veritable  nitryls  of  the  amyloids;  under  which  convenient  term  he  includes 
those  hydrates  of  carbon  which  are  susceptible  of  conversion  into  glucose. 
(Ibid.,  May,  1860,  p.  856.) 

In  1861,  Messrs.  Fischer  and  Boedeker  announced  the  production  of  fer- 
mentescible  sugar  by  the  action  of  dilute  acids  on  cartilage,  and  showed  that 
the  ingestion  of  gelatine  increases  the  amount  of  sugar  in  normal  human 
\irine.  These  authors  seem,  by  the  abstract  before  me  (Repertoire  de  Chimie 
Pure,  July,  1861,  from  Ann.  der  Chem.  und  Pharm.,  CXVII.  p.  Ill),  to 
ignore  alike  my  own  observations  and  those  of  Gerhardt,  who  twenty  years 
since  showed  that,  by  long  boiling  with  dilute  sulphuric  acid,  there  is  formed 
from  gelatine  a  sweet,  fermentescible  sugar,  together  with  a  large  amount  of 
sulphate  of  ammonia.  (Precis  de  Chimie  Organique,  II.  p.  521.) 


X.]  ON  THE  ORIGIN  OF  COAL.  181 

from  the  microscopical  studies  of  Dawson  and  others  that,  although 
it  is  doubtless  true  that  cellulose  may  yield  bodies  having  the 
chemical  composition  of  bituminous  coal,  and  even  bitumens,  by  a 
process  of  alteration  such  as  I  have  described  above,  the  chief 
source  of  such  coal  in  the  older  coal  measures  has  been  epidermal 
tissues,  which  diner  from  cellulose  in  being  much  richer  in  carbon 
and  hydrogen.  These  tissues,  as  remarked  by  Dawson,  "  are  very 
little  liable  to  decay,  and  resist  more  than  most  other  vegetable 
matters  aqueous  infiltration,  properties  which  have  caused  them  to 
remain  unchanged  and  resist  the  penetration  of  mineral  substances 
more  than  other  vegetable  tissues.  These  qualities  are  well  seen 
in  the  bark  of  our  American  white  birch  (Betida  alba).  It  is  no 
wonder  that  materials  of  this  kind  should  constitute  considerable 
portions  of  such  vegetable  accumulations  as  the  beds  of  coal,  and  that 
when  present  in  large  proportion  they  should  afford  richly  bitu- 
minous beds.  All  this  agrees  with  the  fact  apparent  on  examination 
of  common  coal,  that  the  greater  number  of  its  purest  layers  con- 
sist of  the  flattened  bark  of  sigillarise  and  similar  trees,  just  as  any 
single  flattened  trunk  imbedded  in  shale  becomes  a  layer  of  pure 
coal.  It  also  agrees  with  the  fact  that  other  layers  of  coal,  and 
also  the  cannels  and  earthy  coals,  appear  under  the  microscope  to 
consist  of  finely  comminuted  particles,  principally  of  epidermal 
tissues,  not  only  of  the  fruits  and  spore-cases  of  plants,  but  also 
of  their  leaves  and  stems." 

In  this  connection  I  noticed  in  the  same  paper  the  chemical  com- 
position of  the  epidernjal  or  cortical  tissue  of  plants,  to  which  the 
name  of  suberin  has  been  given,  and  compared  it  with  that  of  the 
spores  of  lycopodium,  and  at  the  same  time  with  cellulose  and  with 
forms  of  coal  and  related  bodies.  The  nitrogen  which  the  first  two 
mentioned  bodies  contain  probably  represents  a  portion  of  albuminoid 
matter,  which  in  lycopodium  is  considerable  in  amount.  For  the 
puqjose  of  comparison  empirical  formulas  corresponding  to  twenty- 
four  equivalents  of  carbon  have  been  calculated  for  these  bodies,  as 
already  done  on  page  176.  We  have  then  as  follows  :  — 

Cellulose C^O,, 

Cork C24H18.,06.T 

Lycopodium CJ4H19.4N05., 

Peat  (Vaux) .  CMH14.4010 

Brown  coal  (Schrotter) CJ4HM.8010.0 

Lignite  (Vaux) <'MHn.300.4 

Bituminous  coal  (Regnault)      .....  C^H^O^ 


182  ON  THE  ORIGIN  OF  COAL.  [X. 

I  further  said,  "  It  will  be  seen  from  this  comparison  that  in  ulti- 
mate composition  cork  and  lycopodium  are  nearer  to  lignite  than 
to  woody  fibre  (cellulose),  and  may  be  converted  into  coal  with  far 
less  loss  of  carbon  and  hydrogen  than  the  latter.  They,  in  fact, 
approach  closer  in  composition  to  resins  and  fats  than  to  wood  ;  and, 
moreover,  like  these  substances,  repel  water,  with  which  they  are 
not  easily  moistened,  and  are  thus  able  to  resist  those  atmospheric 
influences  which  effect  the  decay  of  woody  tissue." 

The  nitrogen  present  in  the  lycopodium  spores,  as  remarked  by 
Dawson,  "  no  doubt  belongs  to  the  protoplasm  in  them,  which  would 
soon  perish  by  decay ;  and,  subtracting  this,  the  cell- walls  of  the 
spores  and  the  walls  of  the  spore-cases  would  be  most  suitable  material 
for  the  production  of  bituminous  coal.  But  this  suitableness  they 
share  with  the  epidermal  tissue  of  the  scales  of  strobiles  and  of 
the  stems  and  leaves  of  ferns  and  lycopods,  and  above  all  with 
the  thick  corky  envelope  of  the  stems  of  sigillarise  and  similar 
trees  ....  which,  from  its  condition  in  the  prostrate  and  in  the  erect 
trunks  contained  in  the  beds  associated  with  coal,  must  have  been 
highly  carbonaceous  and  extremely  enduring,  and  impermeable  to 
water."  The  substance  known  as  mineral  charcoal  is,  according  to 
Dawson,  derived  from  woody  tissue  and  the  fibres  of  bark.  (See  in 
this  connection  his  paper  on  the  Conditions  of  the  Accumulation  of 
Coal,  Quarterly  Geological  Journal,  XXII.  95.) 

[NOTE  to  page  180.  The  petroleum  of  Pennsylvania,  according  to  Pelouze 
and  Cahours,  yields  by  fractional  distillation  various  liquids  having  the 
common  formula  CnH2M-f-2  (C  =  12),  the  value  of  n  ranging  from  4  to  15, 
(corresponding  to  C^H^  .  .  .  C^H^  in  the  notation  adopted  in  the  preceding 
pages),  and  the  boiling-point  from  0°  to  160°  C.  Of  this  series,  which  also  in- 
cludes the  paraffines,  the  first  term  is  marsh-gas  or  formene,  and  the  second  and 
third  belong  to  the  ethylic  and  propylic  groups,  being  C3H4,  C4H6  and  C6H8  in 
the  above  notation.  The  latter  two,  according  to  Ronalds,  are  found  in  solu- 
tion in  the  crude  petroleum.  The  researches  of  Foucou  and  Fouque  (Comptes 
Rendus,  November  23,  1868)  show  that  while  the  inflammable  gases  from  the 
so-called  Burning  Spring  near  Niagara  Falls,  and  from  an  oil-well  in  Wirtz 
County,  West  Virginia,  are  marsh-gas  with  small  admixtures  of  carbonic  acid, 
the  gases  from  an  oil-well  in  Petrolia,  Ontario,  and  from  Fredonia,  Chatauque 
County,  New  York,  are  mixtures,  in  about  equal  parts,  of  the  second  and  third 
hydrocarbons  of  the  above  series.  The  gas  at  the  latter  locality  is  from  a 
well  sunk  into  the  Genessee  slates,  at  the  summit  of  the  Hamilton  formation, 
which  gives  no  petroleum,  but  has  for  many  years  furnished  the  supply  of 
gas  for»lighting  a  small  town.  The  gas  from  an  oil-well  in  Venango  County, 
Pennsylvania,  contained  besides  the  first  three  bodies  of  the  series  a  portion 
of  the  fourth,  C8H10.  Neither  acetylene,  free  hydrogen,  carbonic  oxide,  nor 
defiant  gas  or  its  homologues  were  detected.] 


XL 


ON  GRANITES  AND  GRANITIC  VEIN- 
STONES. 

(1871-1872.) 

This  paper  appeared  in  three  parts  in  the  American  Journal  of  Science  for  Feb- 
ruary and  March,  1871,  and  for  February,  1872.  The  license  by  which  the  title  is 
made  to  include  a  description  of  certain  calcareous  vein-stones  is  explained  to  the 
reader  under  §§  35  -  37.  Part  I.,  as  originally  printed,  included  §§  1  - 15 ;  part  II., 
§§16-31;  and  part  III.,  §§32-49. 

CONTESTS  OF  SECTIONS.  —  1,  2.  Definitions  of  granite  and  syenite  ;  3. 
Structure  of  granitic  and  gneissic  rocks;  4,  5.  Felsites  and  felsite- 
porphyries;  6.  Gneisses  and  granites  of  New  England;  7.  Granitic 
dikes  and  granitic  vein-stones;  8.  Scheerer's  theory  of  granitic  veins; 
9-10.  Elie  de  Beaumont  on  granites  and  granitic  emanations;  11. 
Granitic  distinguished  from  concretionary  veins;  12.  Von  Cotta  on 
granitic  veins;  13,  14.  The  author's  views  on  the  concretionary  origin 
of  granitic  veins;  15.  The  banded  structure  of  granitic  veins;  16. 
Granitic  veins  of  Maine,  Brunswick;  17.  Topsham,  Paris;  18.  West- 
brook,  Lewiston;  crystalline  limestones;  19.  Danville,  Ketchum;  20. 
Denuded  granitic  masses;  21.  Banded  veins;  Biddeford,  Sherbrooke; 
22.  Veins  at  various  New  England  localities;  23.  Mineral  species  of 
these  veins;  24.  Veins  in  erupted  granites;  25.  Geodes  in  granites; 
26.  Veins  distinguished  from  dikes;  27.  Volger  and  Fournet  on  the 
origin  of  veins;  28,  29.  Certain  fissures  and  geodes  distinguished  from 
veins  opening  to  the  surface;  30,  31.  Temperatures  of  crystallization 
of  granitic  minerals;  32.  Laurentian  gneisses;  33.  PjTOxenites  and 
limestones;  34.  Absence  of  mica-schists;  35.  Classes  of  veins;  36. 
Granitic  vein-stones;  37.  Similar  veins  in  Norway;  38.  Minerals  of 
granitic  veins ;  39.  Evidences  of  concretionary  origin;  banded  structure; 
40.  Incrustations  of  crystals  ;  41.  Skeleton-crystals;  42.  Rounded 
crystals;  43.  Quartz  crystals  in  metalliferous  veins;  44.  Types  of 
vein-stones;  feldspathic;  45.  Calcareous  vein-stones;  46.  Order  of  suc- 
cession of  minerals;  47.  Attitude  of  the  veins;  48.  Calcareous  vein- 
stones in  higher  rocks;  49.  Supposed  eruptive  limestones. 

§   1.  THE  name  of  granite  is  employed  to  designate  a  sup- 
posed eruptive  or  exotic  unstratified  composite  rock,  granular, 


184  GRANITES  AND   GRANITIC  VEIN-STONES.  [XI. 

crystalline  in  texture,  and  consisting  essentially  of  orthoclase- 
feldspar  and  quartz,  with  an  admixture  of  mica,  and  frequently 
of  a  triclinic  feldspar,  either  oligoclase  or  albite.  This  is  the 
definition  of  granite  given  by  most  writers  on  lithology,  and 
applies  to  a  great  portion  of  what  are  commonly  called  granitic 
rocks;  there  are,  however,  crystalline  granite-like  aggregates 
in  which  the  mica  is  replaced  by  a  dark  colored  hornblende  or 
amphibole,  and  to  such  a  compound  rock  many  authors  have 
given  the  name  of  syenite,  while  to  those  in  which  mica  and 
hornblende  coexist  the  name  of  syenitic  granite  is  applied. 
It  is  observed  that  in  certain  of  these  hornblendic  granites  the 
quartz  becomes  less  in  amount  than  in  ordinary  granites,  and 
finally  disappears  altogether,  giving  rise  to  a  rock  composed  of 
orthoclase  and  hornblende  only.  To  such  a  binary  aggregate 
Von  Cotta  and  Zirkel  would  restrict  the  term  "  syenite,"  which 
was  already  defined  by  D'Omalius  d'Halloy  to  be  a  crystalline 
aggregate  of  hornblende  and  feldspar ;  by  which  orthoclase- 
feldspar  may  be  understood,  since  he  describes  varieties  of 
syenite  as  passing  into  diorite,  —  a  name  by  most  modern 
lithologists  restricted  to  a  compound  of  albite,  or  some  more 
basic  triclinic  feldspar,  with  hornblende.  It  is  apparently  by 
failing  to  appreciate  the  distinction  between  orthoclase  and 
triclinic  feldspar,  in  this  connection,  that  Haughton  has  lately 
described,  under  the  name  of  syenite,  rocks  which  are  composed 
of  crystalline  labradorite  and  hornblende. 

§  2.  Naumann,  regarding  orthoclase  and  quartz  as  the  essen- 
tial constituents  of  granite,  designates  those  aggregates  which 
contain  mica  as  mica-granites,  and  thus  distinguishes  them 
from  hornblende-granites,  in  which  the  mica  is  replaced  by 
hornblende.  These  definitions  seem  the  more  desirable,  as  the 
name  of  granite  is  popularly  applied  both  to  the  hornblendic 
and  the  micaceous  aggregates  of  orthoclase  and  quartz.  There 
are  not  wanting  examples  of  well-defined  rocks  of  this  kind  in 
which  both  mica  and  hornblende  are  almost  or  altogether  want- 
ing. Such  rocks  have  been  designated  binary  granites,  a  term 
which  it  will  be  well  to  retain.  Chloritic  and  talcose  granites, 
into  the  composition  of  which  chlorite  and  talc  enter,  need 


XL]  GRANITES  AND   GRANITIC  VEIN-STONES.  185 

only  be  mentioned  in  this  connection.  The  name  of  syenite, 
so  often  given  to  hornblendic  granites,  will,  in  accordance  with 
the  views  already  expressed,  be  restricted  to  rocks  destitute  of 
quartz.  While  the  disappearance  of  this  mineral  from  horn- 
blendic granites  is  held  to  give  rise  to  a  true  syenite,  the  same 
process  with  micaceous  granites  affords  a  quartzless  rock  con- 
sisting of  orthoclase  and  mica,  for  which  we  have  no  name. 
Great  masses  of  an  eruptive  rock,  granite-like  in  structure,  and 
consisting  of  crystalline  orthoclase  or  sanidin,  without  any 
quartz,  occur  in  the  province  of  Quebec.  This  rock  contains 
in  some  cases  a  small  admixture  of  black  mica,  and  in  others 
an  equally  small  proportion  of  black  hornblende.  The  latter 
variety  might  be  described  as  syenite,  but  for  the  former  we 
have  no  distinctive  name ;  and  I  have  described  both  of  these 
by  the  name  of  granitoid  trachytes,  a  term  which  I  adopted  the 
more  willingly  on  account  of  the  peculiar  composition  of  the 
feldspar,  and  also  because  compact  and  finely  granular  rocks 
in  the  same  region,  having  a  similar  chemical  composition,  pre- 
sent all  the  characters  of  typical  trachytes,  and  apparently 
graduate  into  the  granitoid  rocks  just  noticed,*  In  all  at- 
tempts to  define  and  classify  compound  rocks,  it  should  be 
borne  in  mind  that  they  are  not  definite  lithological  species, 
but  admixtures  of  two  or  more  mineralogical  species,  and  can 
only  be  arbitrarily  defined  and  limited. 

§  3.  Having  thus  defined  the  mineral  composition  of  granitic 
rocks,  we  proceed  to  notice  their  structure.  Gneiss  has  the 
same  mineral  elements  as  granite,  but  is  distinguished  by  the 
more  or  less  stratified  and  parallel  arrangement  of  its  constitu- 
ents ;  and  lithologists  are  aware  that  in  certain  varieties  of 
gneiss  this  structure  is  scarcely  evident,  except  on  a  large 
scale ;  so  that  the  distinction  between  gneiss  and  granite  rests 
rather  on  geognostical  than  on  lithological  grounds.  To  the 
lithologist,  in  fact,  the  granitoid  gneisses  are  simply  more  or 
less  stratiform  granites,  while  it  belongs  to  the  geologist  to 
consider  whether  this  structure  has  resulted  from  a  sedimentary 

*  American  Jcmraal  of  Science  (2),  XXXVIII.  95.     See  also  Zirkel,  Petro- 
graphie,  11.179. 


186  GRANITES  AND   GRANITIC  VEIN-STONES.  [XI. 

deposition,  or  from  the  flowing  of  a  semi-fluid  heterogeneous 
mass  giving  rise  to  a  stratiform  arrangement.* 

§  4.  The  rocks  having  the  mineralogical  composition  of 
granites  present  a  gradual  passage  from  the  coarse  structure  of 

[*  This  process  has  been  particularly  described  in  my  Contributions  to 
Lithology,  where  also  the  principles  of  lithological  classification  are  discussed 
at  length.  (American  Journal  of  Science  for  March  and  July,  1864. )  A  strati- 
form structure  in  eruptive  rocks  is  there  said  to  be  due  to  "the  arrangement 
of  crystals  during  the  movement  of  the  half-liquid  crystalline  mass,  but  it  may 
in  some  instances  arise  from  the  subsequent  formation  of  crystals  arranged 
in  parallel  planes."  In  the  same  paper,  in  describing  the  dolerite  of  Montar- 
ville,  the  alternations  of  a  coarse  variety,  porphyritic  from  the  presence  of 
large  crystals  of  augite,  with  a  finer  grained  and  whiter  variety  is  noticed; 
the  two  being  "  arranged  in  bands,  whose  varying  thickness  and  curving  lines 
suggest  the  notion  that  they  have  been  produced  by  the  flow  and  the  partial 
commingling  of  two  fluid  masses."  At  Mount  Royal  also,  as  there  described, 
"mixtures  of  augite  with  feldspar  are  met  with,  constituting  a  granitoid 
dolerite,  in  parts  of  which  the  feldspar  predominates,  giving  rise  to  a  light 
grayish  rock.  Portions  of  this  are  sometimes  found  limited  on  either  side  by 
bands  of  nearly  pure  black  pyroxenite,  giving  at  first  sight  an  aspect  of  strati- 
fication. The  bands  of  these  two  varieties  are  found  curiously  contorted  and 
interrupted,  and,  as  at  Montarville,  seem  to  have  resulted  from  movements  in 
a  heterogeneous  pasty  mass,  which  have  effected  a  partial  blending  of  an  augitic 
magma  with  another  more  feldspathic  in  its  nature." 

Further  illustrations  of  this  are  given  by  the  author  in  a  communication, 
to  the  Boston  Society  of  Natural  History,  January  7,  1874.  Among  these 
was  a  specimen  from  Groton,  Connecticut,  in  which  a  large  angular  fragment 
of  strongly  banded  micaceous  gneiss  is  enclosed  in  a  fine-grained  eruptive 
granite,  the  mica  plates  in  which  are  so  arranged  as  to  show  a  beautiful  and 
even  stratification  in  contact  with  the  broken  edges  of  the  gneiss,  but  at  right 
angles  to  the  strata  of  the  latter.  Another  example  is  afforded  by  the  erup- 
tive diorite  from  the  mesozoic  sandstone  of  Lambertville,  New  Jersey,  which 
is  conspicuously  marked  by  light  and  dark  bands  due  to  the  alternate  pre- 
dominance of  one  or  the  other  of  the  constituent  minerals  ;  and  still  another 
in  a  fine-grained  dark  micaceous  dolerite  dike  from  the  Trenton  limestone  at 
Montreal,  in  which  the  abundant  laminae  of  mica  (probably  biotite)  are  ar- 
ranged parallel  to  the  walls  of  the  dike.  A  similar  banded  structure  is  seen 
in  glacier-ice  and  in  furnace-slags.  Some  geologists  have  from  facts  of  this 
kind  been  led  to  suppose  that  the  banded  structure  of  great  areas  of  gneiss  was 
caused  by  movements  of  flow  in  a  solidifying  mass,  and  not  by  successive  de- 
posits of  dissolved  or  suspended  material  from  a  watery  medium.  While  ad- 
mitting the  frequent  occurrence  of  this  structure  in  eruptive  7'ocks,  and  the 
necessity  in  many  cases  of  a  careful  geognostical  study  to  determine  to  which 
class  a  stratiform  rock  should  be  referred,  it  was  maintained  that  the  great 
areas  of  gneissic  rocks  are  of  aqueous  origin,  and  were  deposited  in  successive 
horizontal  layers  with  their  associated  limestones,  quartzites,  and  iron-oxides.] 


XL]  GRANITES  AND  GRANITIC  VEIN-STONES.  187 

ordinary  micaceous,  hornblendic,  and  binary  granites  to  finely 
granular  and  even  impalpable  mixtures  of  the  constituent  min- 
erals, constituting  the  rocks  known  as  felsite,  eurite,  and  petro- 
silex.  These  rocks  are  often  porphyritic  from  the  presence  of 
crystals  of  orthoclase,  and  sometimes  of  crystals  or  grains  of 
quartz  imbedded  in  the  finely  granular  or  impalpable  paste. 
These  feLsites  and  felsite-porphyries  (orthophyres)  are,  in  very 
many  cases  at  least,  stratified  or  indigenous  rocks,  and  they  are 
sometimes  found  associated  with  granular  aggregates  of  different 
degrees  of  coarseness,  which  show  a  transition  from  true  felsites 
into  granitic  gneisses.  The  resemblances  in  ultimate  composi- 
tion between  felsites,  granites,  and  granitic  gneisses  are  so  close 
that  it  cannot  be  doubted  that  their  differences  are  only  struc- 
tural. 

§  5.  Felsites  and  felsite-porphyries  or  orthophyres  are  well 
known  in  eastern  Massachusetts,  at  Lynn,  Saugus,  Marblehead, 
and  Newburyport,  and  may  be  traced  from  Machias  and  East- 
port  in  Maine,  along  the  southern  coast  of  K^ew  Brunswick  to 
the  head  of  the  Bay  of  Fundy,  with  great  uniformity  of  type, 
though  in  every  place  subject  to  considerable  variations,  from 
a  compact  jasper-like  rock  to  more  or  less  coarsely  granular  va- 
rieties, all  of  which  are  often  porphyritic  from  feldspar  crystals, 
and  sometimes  include  grains  or  crystals  of  quartz.  The  colors 
of  these  rocks  are  generally  some  shade  of  red,  varying  from 
flesh-red  to  purple  ;  pale  yellow,  gray,  greenish,  and  even  black 
varieties  are  however  occasionally  met  with.  These  rocks  are, 
throughout  this  region,  distinctly  stratified,  and  are  closely  as- 
sociated with  dioritic,  chloritic,  and  epidotic  strata.  They  ap- 
parently belong,  like  these,  to  the  great  Huronian  system. 

[Stratiform  rocks,  seemingly  identical  with  these  quartziferous 
feldspar-porphyries,  abound  in  Missouri,  where  they  are  asso- 
ciated with  the  iron-ores  of  Iron  Mountain  and  Shepard  Moun- 
tain. I  have  also  found  them  over  a  considerable  area  along 
the  north  shore  of  Lake  Superior,  on  an  island  south  of  St.  Ig- 
nace,  and  for  some  distance  along  the  coast  to  the  southwest. 
The  breccia  and  conglomerate  in  which  is  found  the  native 
copper  of  the  Calumet  and  Hecla  and  the  Boston  and  Albany 


188  GRANITES  AND   GRANITIC   VEIN-STONES.  [XI. 

mines  of  the  Keweenaw  peninsula,  on  the  south  shore  of  the 
same  lake,  is  made  up  in  large  part  of  the  ruins  of  similar 
orthophyres.] 

§  6.  Many  of  the  so-called  granites  of  New  England  are 
true  gneisses ;  as,  for  example,  those  quarried  in  Augusta,  Hal- 
lowell,  Brunswick,  and  many  other  places  in  Maine,  which  are 
indigenous  rocks  interstratified  with  the  micaceous  and  horn- 
blendic  schists  of  the  great  White  Mountain  series.  To  this 
class  also,  judging  from .  lithological  characters,  belong  the  so- 
called  granites  of  Concord  and  Fitzwilliam,  New  Hampshire. 
These  indigenous  rocks  are  tenderer,  less  coherent,  and  gener- 
ally finer  grained  than  the  eruptive  granites,  of  which  we  have 
examples  in  the  micaceous  granite  of  Biddeford,  Maine,  and 
the  hornblendic  granites  of  Marblehead  and  Stoneham,  Massa- 
chusetts, and  Newport,  Ehode  Island,  in  all  of  which  localities 
the  contact  of  the  eruptive  mass  with  the  enclosing  rock  is 
plainly  seen,  as  is  also  the  case  farther  eastward,  on  the  St. 
Croix  and  St.  John's  Elvers  in  New  Brunswick,  and  in  the 
Cobequid  Hills  and  elsewhere  in  Nova  Scotia.  The  horn- 
blendic granites  of  Gloucester,  Salem,  and  Quincy,  Massachu- 
setts, seem  also,  from  their  lithological  characters,  to  belong  to 
the  class  of  exotic  or  true  eruptive  granites.*  The  further  dis- 
cussion of  the  'nature  and  origin  of  these  gneisses  and  granites 
is  reserved  for  another  occasion,  and  we  now  proceed  to  notice 
the  history  of  granitic  veins. 

§  7.  The  eruptive  granitic  masses  just  noticed  not  only  in- 
clude fragments  of  the  adjacent  rocks,  especially  near  the  line 
of  contact,  but  very  often  send  off  dikes  or  veins  into  the  sur- 
rounding strata.  The  relation  of  these  with  the  parent  mass  is 
however  generally  obvious,  and  it  may  be  seen  that  they  do 
not  differ  from  it  except  in  being  often  finer  grained.  These 
injected  or  intruded  veins  are  not  to  be  confounded  with  a 
third  class  of  granitic  aggregates,  which  I  have  elsewhere 
described  as  granitic  vein-stones,  or,  to  express  their  supposed 

*  T.  S.  Hunt  on  the  Geology  of  Eastern  New  England,  American  Journal 
of  Science  for  July,  1870,  p.  88;  also  Notes  on  the  Geology  of  the  Vicinity  of 
Boston,  Proc.  Boston  Nat.  Hist.  Soc.,  Oct.  19,  1870. 


XL]  GRANITES  AND  GRANITIC  VEIN-STONES.  189 

mode  of  formation,  endogenous  granites.  They  are  to  the 
gneisses  and  mica-schists,  in  which  they  are  generally  enclosed, 
what  calcite  veins  are  to  stratified  limestones,  and  although 
long  known,  and  objects  of  interest  from  their  mineral  con- 
tents, have  generally  been  confounded  with  intrusive  granites. 

§  8.  Scheerer,  in  his  famous  essay  on  granitic  rocks,  which 
appeared  in  the  Bulletin  of  the  Geological  Society  of  France  in 
1847  (Vol.  IV.  p.  468),  conceives  the  congealing  granitic  rocks 
to  have  been  impregnated  with  "  a  juice,"  which  was  nothing 
else  than  a  highly  heated  aqueous  solution  of  certain  mineral 
matters.  This,  under  great  pressure;  oozed  out,  penetrating 
even  the  stratified  rocks  in  contact  with  the  granite,  filling 
cavities  and  fissures  in  the  latter,  and  depositing  therein  crys- 
tals of  quartz  and  of  hornblende,  the  arrangement  of  which 
shows  them  to  have  been  of  successive  growth.  Neither 
Scheerer  nor  Yirlet  d'Aout,  who  supported  his  views,  however 
(Ibid.,  IV.  p.  493),  extended  them  to  feldspathic  veins,  though 
Daubree,  at  an  earlier  date,  had  described  certain  granitic  veins 
in  Scandinavia  as  having  been  formed  by  secretion,  rather  than 
by  igneous  injection,  as  maintained  by  Durocher. 

§  9.  Elie  de  Beaumont,  starting  from  the  hypothesis  of  a 
cooling  liquid  globe,  imagined  "  a  bath  of  molten  matter  on  the 
surface  of  which  the  first  granites  crystallized."  From  the  ruins 
of  these  were  formed  the  first  sedimentary  deposits,  but  directly 
beneath  were  other  granitic  masses,  which  became  fixed  imme- 
diately afterward.  "  Some  parts  of  these  masses,  coagulated 
from  the  commencement  of  the  cooling  process,  but  not  com- 
pletely solidified,  were  then  erupted  through  the  sedimentary 
deposits  "  just  mentioned.  "  In  these  jets  of  pasty  matter  " 
were  contained  many  of  the  rarer  elements  of  the  granitic  mag- 
ma, which  were  thus  concentrated  in  the  outermost  portions  of 
the  granitic  crust,  and  in  the  ramifications  formed  by  these 
portions  in  the  masses  through  which  they  were  forced  by 
the  eruptive  agents.  Those  portions  of  the  granitic  masses, 
and  their  ramifications,  in  which  these  rarer  elements  are  con- 
centrated, are  distinguished  from  the  rest  of  the  masses  alike 
by  their  exterior  position  and  their  peculiar  structure.  They 


190  GRANITES  AND  GRANITIC  VEIN-STONES.  [XI. 

are  often  coarse-grained,  and  include  the  pegmatites,  tourmaline- 
granites,  and  veins  carrying  cassiterite  and  columbite,  frequent- 
ly abounding  in  quartz.  These  mineral  products  are  to  be 
regarded  as  emanations  from  the  granite,  and  are  described  as 
a  granitic  aura,  constituting  what  Humboldt  has  called  the 
penumbra  of  the  granite.  (Bull.  Soc.  Geol.  de  France  (2),  IV. 
1249.  See  particularly  pages  1295,  1321,  and  1323.) 

§  10.  While  Fournet,  Durocher,  and  Riviere  conceived  the 
granitic  magma  to  have  been  purely  anhydrous,  and  in  a  state 
of  simple  igneous  fusion,  Elie  de  Beaumont  maintained,  with 
Poulett  Scrope  and  Scheerer,  that  water  had  in  all  cases  inter- 
vened, and  that  a  few  hundredths  of  water  might,  at  a  low 
red  heat,  have  given  rise  to  the  condition  of  imperfect  liquidity 
which  he  imagined  for  the  material  of  the  injected  granites. 
The  coarsely  crystalline  granitic  veins  were,  according  to  him, 
veins  of  injection,  and  he  speaks  of  them  as  examples  in  which 
"  the  phenomena  essential  to  the  formation  of  granite  had  been 
manifested  with  the  greatest  intensity."  The  granitic  emana- 
tions, which  are  supposed  to  have  furnished  the  material  of 
these  veins,  appear  to  be  regarded  by  him  as  the  result  of  a 
process  of  eliquation  from  the  congealing  granitic  mass.  De 
Beaumont  is  careful  to  distinguish  between  them  and  those 
emanations  which  are  dissolved  in  mineral  waters,  or  are  ex- 
haled as  volcanic  vapors  (page  1324).  To  the  agency  of  such 
waters  he  ascribes  the  formation  of  concretionary  veins,  which 
are  generally  characterized  by  their  symmetrically  banded 
structure.  He  further  adds  that  granites,  as  to  their  mode  of 
formation,  offer  a  character  intermediate  between  ordinary  veins 
and  volcanic  and  basic  rocks.  This  is  conceivable  as  regards 
granitic  veins,  since  these,  according  to  him,  although  formed 
by  injection,  and  not  by  concretion,  result  from  a  process  of 
emanation  from  the  parent  granitic  mass,  which  may  be  de- 
scribed as  a  kind  of  segregation. 

I  have  thus  endeavored  to  give,  for  the  most  part  in  his  own 
words,  the  views  on  the  origin  of  granites  enunciated  by  the 
great  French  geologist  in  his  classic  essay  on  Volcanic  and 
Metalliferous  Emanations,  published  in  1847.  They  belong  to 


XL]  GRANITES  AND  GRANITIC  VEIN-STONES.  191 

the  history  of  our  subject,  and  are  remarkable  as  a  clear  and 
complete  expression  of  those  modified  plutonic  views  which 
are  probably  held  by  a  great  number  of  enlightened  geologists 
at  the  present  time.  My  reasons  for  dissenting  from  them,  and 
the  theories  which  I  offer  in  their  stead,  will  be  shown  in  the 
sequel. 

§11.  Elie  de  Beaumont,  while  regarding  the  formation  of 
granitic  veins  as  a  process  in  which  water  intervened  to  give 
fluidity  to  the  magma,  was  careful  to  distinguish  the  process 
from  that  of  the  production  of  concretionary  veins  from  aque- 
uous  solution,  and  supposed  the  fissures  to  have  been  filled  by 
the  injection  of  a  jet  of  pasty  matter  derived  from  a  consolidat- 
ing granitic  mass.  Daubree  and  Scheerer,  in  describing  the 
granitic  veins  of  Scandinavia,  conceive  the  material  filling 
them  to  have  been  derived  from  the  enclosing  crystalline  strata, 
instead  of  from  an  unstratified  granitic  nucleus,  but  do  not,  so 
far  as  I  am  aware,  compare  their  formation  to  that  of  concre- 
tionary veins.  Their  publications  on  this  subject,  it  should 
be  said,  are  both  anterior  to  the  essay  of  De  Beaumont. 

§  12.  The  notion  that  all  granitic  veins  are  the  result  of 
some  process  of  injection,  and  not  to  be  confounded  with  con- 
cretionary veins,  seems  indeed  to  have  been  general  up  to  the 
present  time.  Even  Von  Cotta,  while  strongly  maintaining  the 
aqueous  and  concretionary  origin  of  metalliferous  veins  in  gen- 
eral, when  describing  those  consisting  of  quartz,  mica,  feldspar, 
tourmaline,  garnet,  and  apatite,  with  cassiterite,  wolfram,  etc., 
which  occur  at  Zinnwald  and  at  Johanngeorgenstadt,  is  at  a 
loss  whether  to  regard  these  veins,  from  their  granitic  character, 
as  igneous-fluid  injections  or  as  concretionary  lodes.  In  sup- 
port of  the  latter  view  he  refers  to  their  more  or  less  regular 
and  symmetrically  banded  structure,  and  while  recalling  the 
fact  that  mica  and  feldspar  may  both  be  formed  in  the  humid 
way,  considers  the  nature  of  these  veins  to  be  very  problemati- 
cal, and  the  question  of  their  origin  a  difficult  one.  (Ore  De- 
posits, Prime's  translation,  1870,  pages  110-  124.) 

§  1 3.  I  have  for  several  years  taught  that  granitic  veins  of 
the  kind  just  referred  to  are  concretionary  and  of  aqueous 


192  GRANITES  AND   GRANITIC  VEIN-STONES.  [XI. 

origin.  In  1863  I  described  certain  veins  in  the  crystalline 
schists  of  the  Appalachian  region  of  Canada,  "  where  flesh-red 
orthoclase  occurs  so  intermingled  with  chlorite  and  white 
quartz  as  to  show  the  contemporaneous  formation  of  the  three 
species.  The  orthoclase  generally  predominates,  often  reposing 
upon  or  surrounded  by  chlorite  ;  at  other  times  it  is  imbedded 
in  quartz,  which  covers  the  latter.  Drusy  cavities  are  also 
lined  with  small  crystals  of  the  feldspar,  and  have  been  subse- 
quently filled  with  cleavable  bitter-spar,  sometimes  associated 
with  specular  iron,  rutile,  and  sulphuretted  copper  ores."  A 
study  of  these  veins  shows  a  transition  from  those  "  containing 
quartz  and  bitter-spar,  with  a  little  chlorite  or  talc,  through 
others  in  which  feldspar  gradually  predominates,  until  we  ar- 
rive at  veins  made  up  of  orthoclase  and  quartz,  sometimes  in- 
cluding mica,  and  having  the  character  of  a  coarse  granite  ;  the 
occasional  presence  of  sulphurets  of  copper  and  specular  iron 
characterizing  all  of  them  alike.  It  is  probable  that  these,  and 
indeed  a  great  proportion  of  quartzo-feldspathic  veins,  are  of 
aqueous  origin,  and  have  been  deposited  from  solutions  in 
fissures  of  the  strata,  precisely  like  metalliferous  lodes.  This 
remark  applies  especially  to  those  granitic  veins  which  include 
minerals  containing  the  rarer  elements.  Among  these  are 
boron,  phosphorus,  fluorine,  lithium,  caesium,  rubidium,  gluci- 
num,  zirconium,  tin,  and  columbium ;  which  characterize  the 
mineral  species  apatite,  tourmaline,  lepidolite,  spodumene, 
beryl,  zircon,  allanite,  cassiterite,  columbite,  and  many  others." 
(Geology  of  Canada,  pp.  476,  644  ;  and  ante,  p.  33.) 

In  this  connection  I  referred  to  the  occurrence  of  orthoclase 
with  quartz,  calcite,  zeolites,  epidote,  and  native  copper  in  cer- 
tain mineral  veins  of  Lake  Superior,  so  well  described  by  Pro- 
fessor J.  D.  Whitney.  (American  Journal  of  Science  (2), 
XXVIII.  16.)  The  associations,  according  to  him,  show  the 
contemporaneous  crystallization  of  the  copper,  natrolite,  calcite, 
and  feldspar,  which  last  was  found  by  analysis  to  be  a  pure 
potash-orthoclase. 

§  14.  In  1864  this  view  was  still  further  insisted  upon  in 
the  Journal  just  cited  ((2),  XXXVII.  252),  where,  in  speaking 


XL]  GRANITES  AND   GRANITIC  VEIN-STONES.  193 

of  mineral  vein-stones  "  which  doubtless  have  been  deposited 
from  aqueous  solution,"  it  is  added,  "  while  their  peculiar  ar- 
rangement, with  the  predominance  of  quartz  and  non-silicated 
species,  generally  serves  to  distinguish  the  contents  of  these 
veins  from  those  of  injected  plutonic  rocks,  there  are  not 
wanting  cases  in  which  the  predominance  of  feldspar  and  mica 
gives  rise  to  aggregates  which  have  a  certain  resemblance  to 
dikes  of  intrusive  granite.  From  these,  however,  true  veins 
are  generally  distinguished  by  the  presence  of  minerals  contain- 
ing boron,  fluorine,  phosphorus,  caesium,  rubidium,  lithium, 
glucinum,  zirconium,  tin,  columbium,  etc. ;  elements  which  are 
rare,  or  found  only  in  minute  quantities  in  the  great  mass  of 
sediments,  but  are  here  accumulated  by  deposition  from  waters 
which  have  removed  these  elements  from  the  sedimentary  rocks 
and  deposited  them  subsequently  in  fissures." 

In  the  Report  of  the  Geological  Survey  of  Canada  for  1866 
(p.  192),  I  have,  in  describing  the  veins  of  the  Laurentian 
rocks,  insisted  still  further  on  the  distinction  just  drawn  be- 
tween granitic  dikes  and  granitic  vein-stones,  which  latter  I 
have  proposed  to  call  endogenous  rocks,  to  indicate  the  mode 
of  their  formation,  and  to  distinguish  them  from  intrusive  or 
exotic  rocks,  and  sedimentary  or  indigenous  rocks. 

§  15.  The  peculiar  banded  arrangement,  which  is  so  charac- 
teristic in  concretionary  veins  not  granitic  in  composition,  is 
probably  not  less  marked  in  granitic  vein-stones,  and  often  ap- 
pears in  these  in  a  remarkable  manner,  showing  that  they  have 
been  formed  by  successive  depositions  of  mineral  matter,  and 
generally  in  open  fissures.  This  structure,  and  various  pecul- 
iarities to  be  observed  in  granitic  vein-stones,  will  be  best  illus- 
trated by  descriptions  of  various  localities,  most  of  which  I 
have  personally  examined.  It  is  proposed  to  notice,  first,  the 
veins  of  the  gneiss  and  mica-schist  series  of  New  England ; 
and,  secondly,  those  of  the  Laurentian  rocks  of  New  York  and 
Canada.  In  the  latter  class  will  be  noticed  the  more  or  less 
calcareous  vein-stones  into  which  the  Laurentian  granitic  veins 
are  found  to  graduate. 

§  16.  It  is  in  the  series  of  micaceous  schists  with  interstrati- 
9  M 


194  GRANITES  AND  GRANITIC  VEIN-STONES.  [XL 

fied  gneisses  (§6)  which  I  have  elsewhere  provisionally  desig- 
nated the  Terranovan  series  *  [since  called  Montalban],  that  I 
have  seen  concretionary  granitic  veins  in  the  greatest  abundance 
and  on  the  grandest  scale.  This  stratified  system,  which  is 
well  seen  in  the  White  Mountains,  appears  to  extend  south- 
ward along  the  Blue  Eidge  as  far  as  Georgia,  and  northeast- 
ward beyond  the  limits  of  Maine.  It  is  in  this  State  that  I 
have  particularly  studied  the  granitic  vein-ston.es  of  this  system, 
whose  history  may  be  illustrated  by  p,  few  examples  from  notes 
taken  on  the  spot.  In  Brunswick  the  strata  near  the  town  are 
fine  grained,  friable,  dark  colored,  micaceous,  and  hornblendic, 
passing  into  mica-schist  on  the  one  hand,  and  into  well-marked 
gneiss  on  the  other,  and  dipping  to  the  southeast  at .  angles  of 
from  15°  to  40°.  Yery  similar  beds  are  found  in  the  adjoin- 
ing town  of  Topsham,  and  in  both  places  they  include  numer- 
ous endogenous  granitic  veins.  The  course  of  these  veins  is 
generally  northwest,  or  at  right  angles  to  the  strike,  though 
occasionally  for  short  distances  with  the  strike,  and  intercalated 
between  the  beds ;  the  veins  vary  in  breadth  from  a  few  inches 
to  sixty  feet,  and  even  more.  They  generally  consist  in  great 
part  of  orthoclase  and  quartz,  with  some  mica  and  tourmaline, 
and  offer  in  the  associations  and  grouping  of  these  minerals 
many  peculiarities,  which  are  met  with  not  only  in  different 
veins,  but  in  different  parts  of  the  same  vein.  In  some  cases, 
colorless  vitreous  quartz  greatly  predominates,  and  encloses 
crystals  of  milk-white  orthoclase,  often  modified,  and  from  one 
to  several  inches  in  diameter.  At  other  times  pure  vitreous 
quartz  forms  one  or  both  walls,  or  the  centre  of  the  vein,  or 
else  is  arranged  in  bands  parallel  with  the  sides  of  the  vein, 
and  sometimes  a  foot  or  more  in  thickness,  alternating  with 
similar  bands  consisting  wholly  or  in  great  part  of  orthoclase, 

*  American  Journal  of  Science  for  July,  1870,  page  83,  and  Can.  Naturalist, 
V.  p.  198.  —  The  rocks  of  this  White  Mountain  series  are,  in  the  present  state 
of  our  knowledge,  supposed  to  be  newer  than  the  Huronian  system  noticed  in 
§  5,  to  which,  with  Macfarlane  and  Credner,  I  refer  the  crystalline  schists, 
with  associated  serpentines  and  diorites,  of  the  Green  Mountains.  [See  further 
in  this  connection  Paper  XIII.  and  its  Appendix;  also  the  third  part  of  Paper 
XVI.  and  the  Introduction  to  III.] 


XL]  GEANITES  AND   GRANITIC  VEIN-STONES.  195 

or  of  an  admixture  of  this  mineral  with  quartz,  having  the  pe- 
culiar structure  of  what  is  called  graphic  granite,  or  else  pre- 
senting a  finely  granitoid  mixture  of  the  two  minerals,  with 
little  or  no  mica,  and  with  small  crystals  of  deep  red  garnet. 
Prisms  of  black  tourmaline  are  also  met  with  in  these  veins, 
and  more  rarely  beryl  and  even  chrysoberyl.  In  the  rock- 
cutting  on  the  Lewiston  Railroad,  just  below  Topsham  bridge 
over  the  Androscoggin,  there  is  a  fine  exhibition  of  these  veins, 
which  present  alternate  coarser  and  finer  grained  layers,  trav- 
ersed by  long  spear-shaped  crystals  of  dark  mica  passing  from 
one  layer  to  another. 

§  1 7.  A  remarkable  example  of  a  vein  of  considerable  dimen- 
sions is  seen  in  the  feldspar-quarry  in  Topsham,  which  occurs 
in  a  dark  fine-grained  friable  micaceous  schist.  At  the  time 
of  my  visit,  in  1869,  the  limits  of  the  vein  were  not  seen, 
though  large  quantities  of  white  orthoclase  and  of  vitreous 
quartz  had  already  been  extracted.  These  were  each  nearly 
pure,  and  in  alternate  bands,  the  quartz  presenting  drusy  cavi- 
ties lined  with  remarkable  tabular  crystals.  One  band  was 
made  up  in  great  part  of  large  crystals  of  mica,  and  portions 
of  the  vein  consisted  of  a  granular  saccharoidal  feldspar.  The 
famous  locality  of  red,  green,  and  blue  tourmalines,  with  beryl, 
lepidolite,  amblygonite,  cassiterite,  etc.,  at  Mount  Mica  in 
Paris,  Maine,  is  a  huge  granitic  vein,  which,  with  many  others, 
is  included  in  a  dark-colored  very  micaceous  gneiss. 

§  18.  In  Westbrook  numerous  small  veins  of  this  kind, 
holding  coarsely  lamellar  orthoclase  with  black  tourmaline  and 
red  garnet,  intersect  strata  of  fine-grained  whitish  granitoid 
gneiss.  In  Windham  the  dark-colored  staurolite-bearing  mica- 
schist  of  this  series  is  traversed  by  a  granitic  vein  holding  crys- 
tals of  beryl.  In  Lewiston  a  large  vein  of  coarse  graphic 
granite,  holding  black  tourmaline,  and  showing  fine-grained 
bands,  cuts  a  great  mass  of  bluish  gneissoid  limestone,  which 
forms  an  escarpment  near  the  railroad,  about  half  a  mile  below 
the  town.  Tliis  limestone,  which  dips  eastward  about  15°,  is 
interlaminated  with  thin  quartzite  beds,  which  are  seen  on 
weathered  surfaces  to  be  much  contorted.  The  bluish  crystal- 


196  GRANITES  AND   GRANITIC   VEIN-STONES.  [XI. 

line  limestone  is  mixed  with,  grains  of  greenish  pyroxene,  and 
includes  nodular  granitic  masses  of  white  crystalline  orthoclase 
with  quartz,  enclosing  large  plates  of  graphite,  crystals  of  horn- 
blende, and  more  rarely  of  apatite.  These  associations  of  min- 
erals are  met  with  in  the  granitic  veins  of  the  Laurentian 
limestones,  to  "be  noticed  elsewhere.  The  limestone  of  Lewis- 
ton,  however,  appears  to  be  included  in  the  great  mica-schist 
series  of  the  region ;  where  similar  beds,  though  less  in  extent, 
are  met  with  in  various  places,  sometimes  associated  with 
pyroxene,  garnet,  idocrase,  and  sphene.  A  thin  band  of  im- 
pure pyroxenic  limestone,  like  that  of  Lewiston,  occurs  with 
the  mica-schists  on  the  Maine  Central  Railroad,  near  Danville 
Junction ;  and  beds  of  a  purer  crystalline  limestone  were  for- 
merly quarried  in  the  southeast  part  of  Brunswick,  where  they 
are  interstratified  with  thin-bedded  dark  hornblendic  and  mica- 
ceous gneiss,  dipping  southeast  at  a  high  angle. 

§  19.  At  Danville  Junction  strata  of  hornblendic  and  mica- 
ceous gneiss,  passing  into  mica-schists,  dip  southeast  at  moder- 
ate angles,  and  include  huge  veins  of  endogenous  granite.  Two 
of  these  appear  in  the  hill  just  south  of  the  railroad-station, 
apparently  running  with  the  strike  of  the  beds.  They  are 
seen  to  rest  upon  the  mica-schist,  and  in  one  of  them  a  mass  of 
this  rock,  three  feet  in  width,  is  enclosed  like  a  tongue  in  the 
granite,  which  has  a  transverse  breadth  of  about  seventy-five 
feet.  Notwithstanding  the  apparent  intercalation  of  these 
granitic  masses,  the  proof  of  their  foreign  origin  is  evident  in  a 
transverse  fracture  and  slight  vertical  dislocation  of  the  mica- 
schist,  around  the  broken  edges  of  which  the  granite  is  seen  to 
wrap.  The  endogenous  character  of  this  granite  is  well  shown 
by  its  banded  structure ;  belts  of  white  quartz  some  inches 
wide  alternate  with  others  of  coarsely  cleavable  orthoclase, 
while  other  portions  hold  black  tourmalines  and  garnets  of 
considerable  size. 

The  evidence  of  disturbance  of  the  strata  in  connection  with 
these  endogenous  granites  is  seen  on  a  large  scale  at  the  falls 
of  the  Sunday  River  in  Ketchum.  There,  mica-schists  and 
gneisses,  similar  to  those  already  noticed,  enclose  great  masses 


XI.]  GRANITES  AND   GRANITIC  VEIN-STONES.  197 

of  endogenous  granite,  which  are  seen  to  be  transverse  to  the 
strata.  On  one  side  of  such  a  mass  more  than  sixty  feet  wide, 
the  schistose  strata  are  twisted  from  their  regular  northeast 
strike  to  the  northwest,  and  so  enclosed  in  the  granite  as  to 
appear  interstratified  with  it  for  short  distances.  The  banded 
structure  of  the  transverse  granite  veins  is  here  very  marked. 
Some  portions  present  cleavage-planes  of  orthoclase  six  inches 
in  diameter ;  other  parts,  which  are  less  coarse,  abound  in  mica. 
Similar  banded  granite  veins  abound  in  the  adjoining  towns 
of  Newry  and  Xorth  Bethel,  and  sometimes  present  layers  of 
quartz  six  inches  or  more  in  thickness,  beside  large  crystals  of 
mica,  and  more  rarely  apatite.*  These  veins  are  often  irreg- 
ular in  shape  and  bulging  at  intervals,  and  they  sometimes  run 
partially  across  the  beds,  which  seem  to  have  been  distended 
and  disturbed ;  a  fact  which  was  also  observed  in  the  thin- 
bedded  schists  in  contact  with  some  of  the  veins  in  Brunswick, 
and  is  apparently  due  to  the  expansive  force  of  crystallization, 
as  noticed  in  §  27. 

§  20.  The  locality  already  described  at  Danville  offers  an 
instructive  example  of  a  phenomenon  often  met  with  in  the 
region  now  under  consideration,  where  granitic  masses,  resist- 
ing the  actions  which  have  degraded  the  soft  enclosing  schists, 
stand  out  in  relief  on  the  surface,  and  seem  to  constitute  the 
rock  of  the  country.  A  careful  search  will  however  show  that 
they  are  simply  veins  or  endogenous  masses  of  very  limited 
dimensions,  rising  from  out  of  the  mica-schists,  which  are  often 
concealed  by  the  soil.  This  is  well  seen  about  the  lower  falls 
of  the  Presumpscott,  near  Portland,  where  the  mica-schists,  with 
some  fine-grained  gneisses,  dipping  southeast  at  angles  of  from 
30°  to  40°,  enclose  large  numbers  of  granitic  veins,  which, 
though  sometimes  but  a  few  inches  in  breadth,  often  measure 
twenty  or  even  fifty  feet,  and  are  usually  very  coarse  grained, 
with  white  mica,  black  tourmaline,  and  more  rarely  beryl. 

*  A  good  example  of  a  large  vein  of  this  kind  of  intersecting  rocks  of  the 
White  Mountain  series  may  be  seen  in  the  Ramble  in  the  Central  Park,  in 
the  city  of  New  York.  Its  place  is  marked  by  a  great  erratic  block  perched 
directly  over  the  vein. 


198  GRANITES  AND   GRANITIC   VEIN-STONES.  [XL 

They  are  sometimes  transverse  to  the  stratification,  but  more 
often  parallel,  and,  standing  above  the  soil,  are  very  conspicu- 
ous. 

§  21.  We  have  already  noticed  the  exotic  granites  of  Bidde- 
ford,  which  are  intruded  among  fine-grained  bluish  or  grayish 
silicious  strata.  These  latter  are  traversed  by  numerous  veins 
of  endogenous  granite,  which  are  very  unlike  in  aspect  to  the 
intrusive  rock.  One  of  these  veins,  near  Saco  Pool,  has  a 
diameter  of  about  an  inch  and  a  half,  and  presents  on  either 
wall  a  layer  of  yellowish  crystalline  feldspar  about  one  fourth 
of  an  inch  in  thickness,  which  includes  long  plates  of  dark 
brown  mica.  These  penetrate  the  central  portion  of  the  vein, 
which  is  a  broadly  crystalline  bluish  orthoclase,  enclosing 
small  portions  of  quartz,  after  the  manner  of  a  graphic  granite. 
The  yellowish  and  less  coarsely  crystalline  feldspar,  with  its 
accompanying  mica,  had  evidently  lined  the  walls  of  the  vein 
while  the  centre  yet  remained  open,  and  had  moreover  entirely 
filled  a  small  lateral  branch.  The  same  conditions  are  seen  in . 
the  filling  of  other  veins  in  this  vicinity,  which  are  often  much 
larger,  and  present  upon  their  walls  bands  of  an  inch  or  two 
of  the  yellowish  feldspar,  with  mica. 

The  successive  filling  of  a  granitic  vein  is  still  more  clearly 
shown  in  a  specimen  from  Sherbrooke,  Nova  Scotia,  which  I  owe 
to  the  kindness  of  Professor  H.  Y.  Hind.  The  vein,  which  is 
seen  to  be  transverse  to  the  adherent  fine-grained  mica-schist, 
has  a  breadth  of  nearly  four  inches,  about  two  thirds  of  which 
is  symmetrical,  and  is  included  between  two  layers,  perpendic- 
ular to  the  walls,  consisting  of  a  fine-grained  mixture  of  white 
feldspar  and  quartz,  each  about  one  fourth  of  an  inch  thick, 
and  marked  by  subordinate  zones,  more  or  less  quartzose. 
Within  these  two  bands  is  a  coarser  aggregate,  consisting  of 
two  feldspars,  with  some  quartz  and  muscovite,  plates  of  which, 
and  crystals  of  pink  orthoclase,  penetrate  an  irregular  layer  of 
smoky  quartz  varying  from  one  eighth  to  one  half  an  inch  in 
diameter.  This  fills  the  centre  of  the  symmetrical  portion  of 
the  vein,  on  one  side  of  which  is  the  mica-schist,  while  the 
other  is  bounded  by  a  band  of  more  than  half  an  inch  of  fine- 


XI.]  GRANITES  AND   GRANITIC  VEIN-STONES.  199 

grained  granite  with  yellowish-green  mica,  presenting  large 
crystals  of  feldspar  near  the  outer  margin,  where  it  is  succeeded 
by  a  layer  of  pure  smoky  vitreous  quartz  of  about  the  same 
thickness,  whose  outer  surface,  against  the  wall,  shows  irregular 
bosses  or  nodular  masses,  the  depressions  between  which  are 
occupied  by  a  finely  granular  micaceous  aggregate  unlike  any 
other  part  of  the  vein  in  texture.*  This  description  may  Le 
read  in  connection  with  the  remarks  in  §  27. 

Dana  has  described  and  figured  a  similar  granitic  vein, 
banded  with  quartz,  observed  by  him  at  Valparaiso  in  Chili 
(Manual  of  Geology,  1862,  p.  713),t  and  has  moreover  main- 
tained that  such  granitic  veins,  like  ordinary  metalliferous 
lodes,  are  clearly  concretionary  in  their  origin,  and  have  been 
filled  by  slow  and  successive  deposits  from  aqueous  solu- 
tions. His  testimony  to  the  views  which  I  have  advocated  in 
this  paper  had  been  overlooked  by  me,  or  it  would  have  been 
noticed  in  §  12. 

§  22.  The  numerous  granitic  veins  so  well  known  to  miner- 
alogists in  the  mica-schists  and  gneisses  of  New  Hampshire, 
Massachusetts,  and  Connecticut,  including,  among  other  famil- 
iar localities,  Grafton,  Acworth,  Royalston,  Norwich,  Goshen, 
Chesterfield,  Middletown,  and  Haddam,  seem,  from  descrip- 
tions and  from  their  mineral  constituents,  to  be  similar  to  those 
of  Maine,  already  mentioned.  With  the  exception  of  Eoyals- 
ton  and  Haddam,  however,  these  localities  are  as  yet  only 
known  to  me  from  specimens  and  descriptions.  It  is  note- 
worthy that  at  the  former  the  finely  crystallized  beryls  are 
directly  imbedded  in  vitreous  quartz,  and  the  same  is  the  case 
with  the  beryls  of  Acworth  and  the  blue  and  green  tourmalines 
of  Goshen.  A  remarkable  example  of  a  vein  of  this  character 
occurs  in  Buckfield,  Maine,  described  to  me  by  Professor  Brush, 

*  The  banded  structure  is  well  shown  in  a  granitic  vein  which  I  owe  to  Pro- 
fessor Haughton  of  Trinity  College,  Dxiblin,  got  from  Three  Rock  Mountain, 
near  that  city.  It  consists  of  white  orthoclase,  with  quartz  and  some  mica 
and  garnet,  and  exhibits  near  the  middle  two  bands  of  prisms  of  black  tour- 
maline pointing  towards  the  centre,  which  is  filled  with  a  coarsely  crystalline 
orthoolase. 

t  From  U.  S.  Exploring  Expedition,  Report  on  the  Geology,  1849,  p.  570. 


200  GRANITES  AND  GRANITIC  VEIN-STONES.  [XI. 

where  large  isolated  crystals  of  white  orthoclase,  nearly  color- 
less muscovite,  and  brown  tourmaline  occur  in  a  vein  of  vitre- 
ous quartz.  At  Paris  and  at  Hebron,  Maine,  tourmalines  are 
found  penetrating  crystals  of  quartz.  The  flattened  tourma- 
lines and  garnets  found  in  muscovite  at  several  localities  in 
New  England  are  well  known  to  collectors,  and  a  curious  ex- 
ample of  enclosure  has  been  observed  by  Professor  Brush  at 
Hebron,  where  crystals  of  muscovite  are  encased  in  lepidolite. 

§  23.  The  following  list  includes  the  principal  mineral 
species  found  in  these  granitic  veins  in  New  England  :  apatite, 
amblygonite,  triphylline,  autunite,  yttrocerite,  orthoclase,  al- 
bite,  oligoclase,  spodumene,  iolite,  muscovite,  biotite,  lepidolite, 
cookeite,  chlorite,  chlorophyllite,  garnet,  epidote,  tourmaline, 
beryl,  zircon,  quartz,  chrysoberyl,  automolite,  cassiterite,  rutile, 
brookite,  uraninite,,  columbite,  pyrochlore,  scheelite,  and  bis- 
muthine.  As  I  am  not  aware  that  chlorite  has  hitherto  been 
mentioned  as  a  constituent  of  these  veins,  it  may  be  said  that 
it  occurs  in  one  at  Albany,  Maine.  To  the  above  should 
be  added  the  rare  species  nepheline,  cancrinite,  and  sodalite, 
which  have  long  been  known  in  bowlders  of  a  granite-like  rock 
in  Maine.  According  to  information  given  me  by  Professor 
Brush,  green  elseolite  with  white  orthoclase  and  black  biotite 
occurs  in  a  granitic  vein  twenty  feet  in  breadth,  lately  observed 
in  the  northwest  part  of  Litchfield,  Maine. 

§  24.  We  have  seen  that  these  endogenous  veins  are  found 
alike  in  the  gneisses,  mica-schists,  limestones,  and  quartzose 
strata  of  this  region.  They  are  also  met  with  in  the  eruptive 
granites,  small  fissures  in  which  are  sometimes  filled  with 
coarsely  crystalline  orthoclase,  smoky  quartz,  various  micas,  and 
zircon.  Examples  of  this  are  seen  in  the  granites  of  Hamp- 
stead,  New  Brunswick,  and  Mount  Uniacke,  Nova  Scotia.  The 
fine  green  feldspar  of  Cape  Ann,  Massachusetts,  and  the  micas, 
cryophyllite  and  lepidomelane,  with  zircon,  described  by  Pro- 
fessor Cooke,  from  the  same  region,  occur  in  veins  in  the  horn- 
blendic  granites  of  that  locality.  Small  veins  cutting  a  some- 
what similar  rock  at  Marblehead  contain  crystallized  green 
epidote  with  white  quartz  and  red  orthoclase. 


XL]  GRANITES  AND  GRANITIC  VEIN-STONES.  201 

§  25.  The  veins  which  we  have  described  are  frequently  of 
very  limited  extent,  and  seem  to  occupy  short  and  irregular 
fissures,  while  in  other  cases  the  mineral  aggregates  which 
characterize  them  occur  in  nests  or  geodes.  This  is  seen  near 
Fall  Brook,  in  the  Nerepis  valley,  in  New  Brunswick,  where 
the  red  micaceous  granite  is  in  one  part  very  friable,  and  pre- 
sents irregular  geode-like  cavities,  sometimes  several  inches  in 
diameter,  which  are  partially  filled  by  radiating  prisms  of 
black  tourmaline,  accompanied  with  quartz  and  albite  crystals, 
and  more  rarely  small  octahedrons  of  purple  fluorite.  The  en- 
closing granite  is  composed  of  deep  red  orthoclase,  with  small 
portions  of  a  white  triclinic  feldspar,  smoky  quartz,  and  black 
mica.  The  conditions  seen  at  this  place  recall  the  description 
of  the  famous  locality  of  feldspars,  etc.,  at  Fariolo,  near  Baveno, 
in  northern  Italy.  The  rock  of  that  place,  described  as  a 
granite,  resembles,  in  a  specimen  before  me,  some  of  the  intru- 
sive granites  of  New  Brunswick,  and  contains  a  pink  and  a 
white  feldspar,  with  a  little  black  mica.  It  includes  veins  of 
graphic  granite,  and  also  spheroidal  masses,  which  differ  in  tex- 
ture from  the  mass  of  the  rock,  and  present  geodes  of  consider- 
able size,  lined  with  fine  large  red  and  white  crystals  of  ortho- 
clase, accompanied  by  albite,  epidote,  quartz,  fluorite,  and  a 
greenish  mica  (or  chlorite),  all  of  which,  according  to  Fournet, 
are  so  mingled  and  interlocked  as  to  show  that  they  are-  of  con- 
temporaneous origin.  To  these  are  to  be  added,  as  occurring 
in  the  geodes,  prehnite,  calcite,  hyalite,  and  specular  iron.  The 
orthoclase  crystals  often  have  adhering  to  their  opposite  faces 
crystalline  plates  of  albite,  which  are  larger  than  the  planes  to 
which  they  are  attached.  The  crystals  of  orthoclase,  moreover, 
frequently  present  hollowed-out  or  hopper-shaped  faces,  which 
Fournet  happily  describes  as  resulting  from  the  forming  of  the 
framework  or  skeleton  of  the  crystals,  when  the  material  was 
not  sufficient  for  their  completion.  A  process  analogous  to  this 
is  often  seen  in  crystallization,  whether  from  fusion,  solution, 
or  vaporous  condensation,  giving  rise  in  some  cases  to  external 
depressions,  and  in  others  to  internal  cavities  in  the  resulting 
crystals.  Fournet  ascribes  the  formation  of  the  geodes  in  the 
9* 


202  GRANITES   AND   GRANITIC   VEIN-STONES.  [XL 

granite  of  Fariolo  to  a  process  of  shrinking,  and  a  subsequent 
segregation  filling  the  resulting  cavities,  in  which  he  is  forced 
to  recognize  the  intervention  of  water,  though  by  no  means  ad- 
mitting the  aqueous  origin  of  veins,  since  he  holds  even  those 
of  quartz  to  have  been  formed  by  igneous  injection.  (Geologie 
Lyonnaise,  *278.) 

§  26.  When  we  consider  the  cause  which  has  produced  the 
fissures  in  the  mica-schists  and  gneisses  of  New  England, 
which  hold  the  granitic  veins  already  described,  it  is  to  be  re- 
marked that  their  comparative  abundance,  their  shortness  and 
their  irregularity,  distinguish  them  from  the  fissures  which  are 
filled  with  eruptive  rocks.  Examples  of  the  latter  may  be  seen 
near  Danville,  Maine,  where  dikes  of  fine-grained  dolerite  are 
posterior  to  the  endogenous  granitic  veins  here  occurring  in  the 
mica-schist.  These  dikes  may  be  supposed  to  be  dependent 
upon  movements  in  the  earth's  crust  opening  deep  fissures 
which  connected  with  some  softened  rock  far  below.  Through 
such  openings  were  extravasated  the  exotic  rocks,  whether 
granites  or  dolerites,  —  more  or  less  homogeneous  mixtures, 
often  widely  different  in  composition  from  the  encasing  rocks. 
The  endogenous  veins,  on  the  contrary,  are  distinguished  not 
only  by  their  more  or  less  heterogeneous  and  often  banded 
structure,  but  by  the  fact  that  their  principal  constituents  are 
generally  the  mineral  species  common  in  the  adjacent  strata. 

§  27.  Yolger  has  attributed  the  formation  of  the  openings 
containing  concretionary  veins  to  the  force  of  crystallization, 
which  is  shown  to  be  very  great  in  the  congelation  of  water 
and  the  crystallizing  of  salts  in  cavities  and  fissures.  Such  a 
process  once  commenced  in  an  opening  in  a  rock  would,  he 
conceived,  be  sufficient  to  make  still  wider  the  fissure,  which 
might  be  fed  by  fresh  solutions  passing  by  capillarity  through 
the  pores  of  the  rock.  If  this  process  were  to  become  concen- 
trated around  several  points,  the  intermediate  spaces  might  be 
so  opened  that  free  crystallization  could  go  on,  resulting  in  the 
production  of  goedes  in  veins  thus  formed. 

Fournet,  on  the  other  hand,  suggests  that  contraction  in 
the  cooling  of  erupted  granites  gave  origin  to  the  fissures  and 


XL]  GRANITES  AND  GRANITIC  VEIN-STONES.  203 

geodes  now  filled  or  partially  filled  with  crystalline  minerals  at 
Fariolo  ;  we  may  readily  suppose  that  a  process  of  contraction 
attendant  upon  the  crystalline  aggregation  of  the  materials  of 
sedimentary  strata  would  give  rise  to  rifts  or  fissures  therein. 
The  lesions  thus  produced  in  the  solid  rocks  become  more  or 
less  completely  repaired,  if  we  may  so  speak,  by  an  effusion  of 
mineral  matter  from  the  walls,  and  thus  are  generated  geodes, 
irregular  masses,  and  many  veins.  That  the  process  imagined 
by  Volger  may  in  some  cases  intervene,  and  may  act  subse- 
quently to  the  one  just  imagined,  is  highly  probable,  though 
we  are  disposed  to  assign  it  but  a  secondary  place  in  the  pro- 
duction of  vein-fissures.  It  offers,  however,  the  most  plausible 
explanation  of  the  distortion  of  the  thin-bedded  strata  already 
noticed  in  connection  with  some  of  the  concretionary  granitic 
veins  of  Maine,  which  seem,  by  a  process  of  growth,  to  have 
bent  outward  the  adjacent  beds.  The  vertical  transverse  veins 
are,  in  many  cases  at  least,  unsymmetrical,  as  if  they  had 
grown  from  one  side,  while  the  distortion  of  the  beds,  some- 
times attended  by  irregular  concretions  in  the  banded  vein- 
stone, appears  at  the  opposite  wall.  The  notion  that  the  vein- 
fissures  opened  as  crystallization  advanced  has  been  defended 
by  Griiner. 

§  28.  It  is  not  here  the  place  to  discuss  how  far  the  greater 
and  deeper  fissures  of  the  earth  are  dependent  upon  the  con- 
traction of  sediments,  as  just  explained,  or  upon  the  wider 
spread  movements  of  the  earth's  crust,  though  even  of  these  it 
may  be  said  that  they  are  more  or  less  directly  the  results  of  a 
process  of  contraction.  It  should,  however,  be  noted  that  while 
some  fissures  of  this  kind  are  filled  with  dikes  of  erupted  rocks 
(§  26),  others  hold  concretionary  veins,  which  are  to  be  distin- 
guished from  the  class  of  veins  just  described,  inasmuch  as  the 
openings  in  which  they  were  deposited  evidently  communicated 
with  the  surface  of  the  earth.  Examples  of  these  are  seen  in 
the  lead  and  zinc-bearing  veins  with  calcite  and  barytine,  which 
traverse  vertically  the  carboniferous  limestone  in  England,  and 
enclose  in  their  central  portions  material  of  liassic  age,  abound- 
ing in  the  remains  of  a  marine  and  a  fresh- water  fauna,  which 


204  GRANITES  AND   GRANITIC  VEIN-STONES.  [XL 

show  these  veins  to  have  been  deposited  in  fissures  communi- 
cating with  the  surface-waters  of  the  liassic  period.  For  a 
description  of  these  veins  by  Mr.  Charles  Moore,  see  the  Re- 
port of  the  British  Association  for  1869,  and  Amer.  Jour,  of 
Science  (2),  L.  365.  Similar  evidence  is  afforded  by  the  exist- 
ence of  rounded  pebbles  imbedded  in  veins,  as  observed  in 
Bohemia  and  also  in  Cornwall,  where  numerous  pebbles  both 
of  slate  and  quartz  were  found  at  a  depth  of  six  hundred  feet 
in  a  lode,  cemented  by  cassiterite  and  sulphuret  of  copper.  (Ly- 
ell,  Student's  Elements  of  Geology,  p.  593.)  Not  less  instruct- 
ive in  this  connection  are  the  observations  of  Mr.  J.  Arthur 
Phillips,  on  the  silicious  vein-stones  now  in  process  of  forma- 
tion in  open  fissures  in  Nevada.  (L.  E.  and  D.  Phil.  Mag.  (4), 
XXXVI.  321,  422 ;  Amer.  Jour,  of  Science  (2),  XLVII.  138.) 
We  cannot  doubt  that  the  ancient,  like  these  modern  veins 
have  been  channels  for  the  discharge  of  subterranean  mineral 
waters ;  and  it  would  seem  that  while  the  deposition  of  the  in- 
crusting  materials  on  the  walls  of  the  fissure  is  in  part  due  to 
cooling,  and  in  part  perhaps  to  infiltration,  in  some  cases,  of 
precipitants  from  lateral  sources,  it  is  chiefly  to  be  ascribed  to 
the  reduction  of  solvent  power  consequent  upon  the  diminu- 
tion of  pressure  as  the  waters  rise  nearer  to  the  surface.*  This 
conclusion,  deducible  from  the  researches  of  Sorby  on  the  rela- 
tion of  pressure  to  solubility  (ante,  page  65),  I  have  pointed 
out  in  the  Geological  Magazine  for  February,  1868,  p.  57. 
See  also  Amer.  Jour,  of  Science  (2),  L.  27. 

§  29.  There  is  evidently  a  distinction  to  be  drawn  between 
veins  which  have  been  open  channels  and  the  segregated 

*  Of  this  a  remarkable  example  was  afforded  in  1866  at  Goderich,  in  Ontario, 
where,  in  a  boring  at  a  depth  of  1,000  feet,  a  bed  of  rock-salt  was  met,  from 
which  for  a  time  a  saturated  or  rather  supersaturated  brine  Avas  obtained. 
As  an  evidence  of  this,  I  saw  a  cube  of  pure  salt,  one  fourth  of  an  inch  in 
diameter,  which  had  formed  upon  and  around  a  projecting  point  of  an  iron 
valve  in  the  pump,  above  the  surface  of  the  ground.  The  liquid  beneath  a 
pressure  of  1,000  feet  of  brine,  equal  to  about  1,200  feet  of  water,  or  thirty- 
six  atmospheres,  having  taken  up  more  salt  than  it  could  hold  at  the  ordinary 
pressure,  deposited  a  portion  of  it  as  it  reached  the  surface,  and  actually  ob- 
structed thereby  the  action  of  the  pump.  After  a  few  months  of  pumping, 
however,  the  well  ceased  to  afford  a  fully  saturated  brine. 


XL]  KANITES  AND  GRANITIC  VEIN-STONES.  205 

masses  and  geodes  formed"  in  cavities  which  appear  to  have 
been  everywhere  limited  by  the  enclosing  rock.  In  the  former 
case  a  free  circulation  of  the  mineral  solution  would  prevail, 
while  in  the  latter  there  could  be  no  renewal  of  it  except  by 
percolation  or  diffusion  through  the  rock.  A  comparison  be- 
tween the  contents  of  geodes  and  fissure-veins,  whether  in 
granitic  rocks  or  in  fossiliferous  limestones,  will  however  show 
that  these  differences  do  not  sensibly  affect  the  mineral  consti- 
tution of  the  deposits. 

§  30.  The  range  of  conditions  under  which  the  same  mineral 
species  may  be  formed  is  apparently  very  great.  Sorby,  from 
his  investigations  of  the  fluid-cavities  of  crystals,  concludes 
that  the  quartz  which  occurs  with  cassiterite,  mica,  and  feld- 
spar in  the  granitic  veins  of  Cornwall  must  have  crystallized 
at  temperatures  from  200°  to  340°  Centigrade,  and  under  great 
pressure ;  conditions  which  we  can  hardly  suppose  to  have  pre- 
sided over  the  production  of  the  crystallized  quartz  found  in 
the  unaltered  tertiaries  of  the  Paris  basin,  or  the  auriferous 
conglomerates  of  California.  In  like  manner  beryl,  though  a 
common  mineral  of  the  tin-bearing  granite  veins,  like  those 
studied  by  Sorby,  occurs  at  the  famous  emerald-mine  of  Muso, 
in  New  Grenada,  in  veins  in  a  black  bituminous  limestone, 
holding  ammonites,  and  of  neocomian  age,  its  accompaniments 
being  calcite,  quartz,  and  carbonate  of  lanthanum  (parisite). 
Small  crystals  of  emerald  are  disseminated  through  this  argil- 
laceous, somewhat  magnesian  limestone,  which  contains,  more- 
over, a  small  amount  of  glucina  in  a  condition  soluble  in  acids. 
(Lewy,  Annales  de  Chimie  et  de  Physique,  LIIL  1  -  26 ;  and 
Fournet,  Geol.  Lyonnaise,  455.) 

§  31.  To  these  we  may  add  the  production  of  various  hy- 
drated  crystallized  silicates,  including  apophyllite,  harmotome 
and  chabazite,  during  the  historic  period  in  the  masonry  of  the 
old  Roman  baths  at  Plombieres  and  Luxeuil,  and  by  the  ac- 
tion of  waters  at  temperatures  of  from  46°  to  70°  Centigrade 
(ante,  page  25) ;  the  presence  of  apophyllite,  natrolite,  and  stil- 
bite  in  the  lacustrine  tertiary  limestones  of  Auvergne  ;  apophyl- 
lite incrusting  fossil  wood,  and  chabazite  crystals  lining  shells  in 


206  GRANITES  AND   GRANITIC  VEIN-STONES.  [XL 

a  recent  deposit  in  Iceland.  The  association  of  such  hydrated 
silicates  with  orthoclase,  as  already  noticed  (§  13),  and  as  de- 
scribed by  Scheerer,  where  natrolite  and  orthoclase  envelop 
each  other,  showing  their  contemporaneous  formation,  with 
many  other  facts  of  a  similar  kind,  lead  to  the  conjecture  that 
orthoclase,  like  beryl  and  quartz,  and  perhaps  some  other  con- 
stituents of  granitic  veins,  may  have  crystallized  in  many  cases 
at  temperatures  much  lower  than  those  determined  by  Sorby, 
and  that  the  conditions  of  their  production  include  a  consider- 
able range  of  temperature ;  a  conclusion  which  is,  however, 
probably  true  to  some  extent  of  zeolites  also. 

§  32.  It  is  now  proposed  to  consider  the  granitic  vein-stones 
found  in  Laurentian  rocks.  The  stratified  rocks  of  this  ancient 
gneissic  series,  as  I  have  elsewhere  pointed  out,  differ  consider- 
ably from  those  of  the  White  Mountain  series,  which,  with 
their  vein-stones,  have  been  treated  of  in  §§  16-23. 

The  Laurentian  series,  the  Lower  Laurentian  of  Sir  William 
Logan,  as  studied  by  him  in  a  region  to  the  north  of  the  Otta- 
wa, the  only  area  in  which  it  has  yet  been  examined  in  detail, 
appears  to  consist  of  an  alternation  of  conformable  gneissic  and 
calcareous  formations.  The  latter  are  three  in  number,  each 
from  1,000  to  2,000  feet  or  more  in  thickness,  and  separated 
by  still  more  considerable  formations  of  gneiss  and  quartzite,  a 
mass  of  gneiss  of  great  but  unknown  thickness  forming  the  base. 
(Geology  of  Canada,  page  45.)  The  gneissic  rocks  of  the 
series  are  very  firm  and  coherent,  reddish  or  grayish  in  color, 
often  very  coarse  grained  and  granitoid,  sometimes  with  but 
obscure  marks  of  stratification  ;  and  frequently  porphyritic  from 
the  presence  of  large  cleavable  masses  of  reddish  orthoclase, 
occasionally  with  a  white  triclinic  feldspar.  They  are  often 
hornblendic,  and  sometimes  contain  small  quantities  of  dark 
colored  mica.  A  white  granitoid  gneiss,  composed  chiefly  of 
orthoclase  and  quartz,  sometimes  contains  an  abundance  of  red 
iron-garnet.  The  latter  mineral  is  often  disseminated,  or  forms 
subordinate  beds  in  the  quartzites  of  the  series. 

§  33.  With  the  crystalline  limestones  of  the  calcareous  parts 
of  the  series  are  often  found  strata  made  up  of  other  minerals, 


XL]  GRANITES  AND   GRANITIC  VEIN-STONES.  207 

to  the  entire  exclusion  of  carbonate  of  lime,  by  an  admixture  of 
which,  however,  they  graduate  into  the  adjacent  limestones. 
These  beds  generally  consist  of  pyroxene,  sometimes  nearly 
pure,  and  at  other  times  mingled  with  a  magnesian  mica,  or 
with  quartz  and  orthoclase,  often  associated  with  hornblende, 
serpentine,  magnetite,  sphene,  and  graphite.  These  pyroxenite 
rocks  are  generally  gneissoid  or  granitoid  in  structure,  and 
sometimes  very  coarse  grained.  They  occasionally  assume  a 
great  thickness,  and  are  then  often  interstratified  with  beds  of 
granitoid  orthoclase-gneiss,  into  which  the  quartzo-feldspathic 
pyroxenites  pass  by  a  gradual  disappearance  of  the  pyroxene. 
The  limestones  often  include  serpentine,  pyroxene,  hornblende, 
phlogopite,  quartz,  orthoclase,  magnetite,  and  graphite  ;  so  that 
the  same  minerals  are  common  to  them  and  to  the  pyroxenic 
strata,  which  may  be  looked  upon  as  marking  the  transition 
between  the  gneissic  and  the  calcareous  parts  of  the  series. 
These  strata,  marked  by  the  predominance  of  calcareous  and 
magnesian  silicates,  appear,  so  far  as  known,  to  accompany 
each  of  the  limestone  formations  of  the  Laurentian,  sometimes, 
however,  developed  to  a  greater  and  sometimes  to  a  less 
extent. 

§  34.  I  have  elsewhere  called  attention  to  the  fact  that  the 
highly  micaceous  schists  and  the  argillites  of  the  Green  Moun- 
tain and  White  Mountain  series  of  rocks  are,  so  far  as  known, 
wanting  in  the  Laurentian,  and  with  them  the  characteristic 
minerals  of  the  latter  series,  staurolite,  andalusite,  and  cyanite. 
There  are,  however,  beds  of  a  highly  micaceous  rock  in  the 
Laurentian  which  contain  an  unctuous  magnesian  mica  with  a 
pyroxenic  admixture ;  these  are  very  unlike  the  mica-schists 
composed  of  a  non-magnesian  mica  and  quartz,  with  orthoclase, 
which  abound  in  the  White  Mountain  rocks.  These  magnesian 
beds  belong  to  the  calcareous  horizons  in  the  Laurentian 
series,  at  which  also  occur  the  most  numerous  veins  and  the 
principal  minerals  of  economic  .value.  It  is  also  along  these 
horizons,  marked  by  softer  rocks,  that  the  valleys  and  the  arable 
lands  of  the  Laurentian  areas  are  chiefly  found,  and  for  this 
reason,  also,  the  mineralogy  of  these  parts  is  better  known  than 


208  GRANITES  AND  GRANITIC   VEIN-STONES.  [XI. 

that  of  the  harder  gneissic  portions.  The  above  observations 
on  the  lithological  character  of  the  stratified  rocks  are  impor- 
tant on  account  of  the  relations  between  these  and  the  included 
veins,  in  which  the  characteristic  minerals  of  the  gneissic  and 
calcareous  rocks  are  often  found  associated. 

§  35.  The  history  of  these  veins,  as  seen  in  the  Laurentian 
rocks  of  the  Laurentides  in  Canada,  the  Adirondacks  of  northern 
New  York,  and  the  Highlands  of  southern  New  York  and  New 
Jersey,  has  been  discussed  at  length  by  the  author  in  an  essay 
on  The  Mineralogy  of  the  Laurentian  Limestones,  in  the  Eeport 
of  the  Geological  Survey  of  Canada  for  1863-66,  pages  181  - 
223.*  In  this  essay,  .which  will  be  frequently  referred  to  in 
the  present  paper,  the  vein-stones  found  in  the  Laurentian  rocks 
have  been  noticed  under  three  heads  :  First,  metalliferous  veins 
carrying  galenite,  blende,  pyrite,  and  chalcopyrite  in  a  gangue  of 
calcite,  sometimes  with  celestine  and  fluorite  ;  these,  which  are 
of  paleozoic  age  or  still  younger,  cut  the  Potsdam  sandstone,  the 
Calciferous  sand-rock,  and  probably  also  the  overlying  Trenton 
limestones.  Second,  quartzo-feldspathic  veins  with  muscovite, 
tourmaline,  zircon,  etc.  These  veins  I  have  described  as  passing 
by  insensible  gradations  into  the  third  class,  in  which  calcite 
and  apatite,  with  pyroxene,  phlogopite,  and  other  calcareous  and 
magnesian  silicates  predominate,  though  frequently  accompa- 
nied by  quartz  and  orthoclase.  These  veins  are  older  than  the 
Potsdam  sandstone,  which  rests  upon  their  eroded  outcrops, 
and  sometimes  includes  worn  fragments  of  apatite  derived  from 
them. 

§  36.  It  is  these  last  two  classes  which  it  is  proposed  to  con- 
sider in  the  present  paper  under  the  name  of  granitic  vein-stones. 
In  justification  of  the  extension  of  the  term  "  granitic  "  to  the 
whole  of  this  series  of  veins,  it  must  be  repeated,  that  it  is  not 
possible  to  draw  a  line  of  distinction  between  those  in  which 
quartz,  and  orthoclase  are  the  characteristic  minerals,  and  those 
in  which  calcite,  apatite,  pyroxene,  and  phlogopite  prevail, 

*  This  essay  is  reprinted,  with  some  additions,  in  the  Report  of  the  Regents 
of  the  University  of  New  York  for  1867,  Appendix  E.  The  reader's  attention 
is  called  to  the  note  on  the  Hastings  rocks,  at  the  close  of  that  reprint. 


XL]  GRANITES  AND  GRANITIC  VEIN-STONES.  209 

sometimes  to  the  entire  exclusion  of  quartz  and  feldspar,  both 
of  which  minerals  are,  however,  frequently  intermixed  with 
the  preceding  species  in  the  same  aggregate.  In  one  example, 
in  Burgess,  Ontario,  the  sides  of  a  large  vein  are  occupied  by 
a  mixture  of  calcite  and  apatite,  while  the  centre  is  filled  by  a 
vertical  granite-like  layer  of  reddish  orthoclase,  with  a  little 
quartz  and  green  apatite.  Of  another  vein  in  the  township  of 
Lake,  in  Ontario,  one  portion  was  found  to  consist  of  calcite 
with  yellow  phlogopite,  while  an  adjacent  part  consisted  of 
quart^,  with  brown  tourmaline,  bismuthine,  native  bismuth, 
and  graphite. 

§  37.  The  resemblance  between  the  minerals  of  these  Lau- 
rentian  vein-stones  and  the  same  species  brought  from  Norway 
was  noticed  so  long  ago  as  1827,  by  Dr.  William  Meade 
(American  Journal  Science  (1),  XII.  303).  Daubree,  in  his 
account  of  the  metalliferous  deposits  of  Scandinavia,  published 
in  1843  (Annales  des  Mines  (4),  IV.  199,  282),  has  given  us 
a  careful  description  of  the  veins  from  which  these  minerals 
are  derived.  From  this,  together  with  the  observations  of 
Scheerer  and  Durocher,  we  are  enabled  to  compare  these  vein- 
stones with  those  of  the  Laurentian  rocks  in  North  America, 
and  show,  as  I  have  —  in  the  essay  above  referred  to  —  done 
in  detail,  and  for  each  principal  species,  the  great  similarity 
which  exists  between  the  two.  In  the  so-called  Primitive 
Gneiss  formation  of  Scandinavia  these  veins  occur  either  in 
gneiss,  or  in  a  gneissoid  rock  consisting  of  various  admixtures 
of  pyroxene,  hornblende,  garnet,  epidote,  and  mica,  the  whole 
associated  with  crystalline  limestones.  The  veins  which  abound 
in  the  gneiss  near  the  iron-mines  of  Arendal,  in  Norway,  accord- 
ing to  Daubree,  though  occasionally  containing  calcite,  apatite, 
hornblende,  and  scapolite,  are  sometimes  destitute  of  all  calca- 
reous and  magnesian  minerals,  and  become  granite-like  aggre- 
gates of  orthoclase  and  quartz.  He  hence  describes  these/veins, 
as  a  whole,  though  frequently  abounding  in  lamellar  calcite,  as 
essentially  granitic  in  character.  As  already  noticed  in  §  8, 
Daubree  agrees  with  Scheerer  in  regarding  these  vein-stones  as 
produced  by  a  process  of  secretion,  in  opposition  to  Durocher, 


210  GRANITES  AND  GRANITIC  VEIN-STONES.  [XI. 

who  looked  upon  them  as  having  been  formed  by  igneous 
injection. 

§  38.  The  principal  mineral  species  known  in  the  correspond- 
ing vein- stones  of  the  Laurentian  rocks  of  North  America  are 
the  following :  calcite,  dolomite,  fluorite,  apatite,  serpentine, 
chrysolite,  chondrodite,  wollastonite,  hornblende,  pyroxene,  pyral- 
lolite,  gieseckite,  scapolite,  petalite,  ortkoclase,  oligoclase,  albite, 
muscovite,  phlogopite,  seybertite,  tourmaline,  garnet,  idocrase,  epi- 
dote,  allanite,  zircon,  spinel,  chrysoberyl,  corundum,  quartz, 
sphene,  rutile,  menaccanite,  magnetite,  hematite,  pyrite,  and 
graphite.  To  which  may  be  added  some  rarer  species,  such  as 
tephroite,  willemite,  franklinite,  zincite,  warwickite,  found  in  a 
few  localities  only,  and  others  of  less  importance.  Of.  the 
above  list,  those  species  whose  names  are  in  italics  have  been 
recognized  as  constituent  minerals  in  the  stratified  rocks  in 
which  the  veins  occur. 

The  most  important  species  in  these  vein-stones  are  calcite, 
quartz,  orthoclase,  phlogopite,  pyroxene,  apatite,  and  graphite, 
of  which  some  one  or  more  will  generally  be  found  to  prevail 
in  the  veins  in  question.  The  greater  part  of  the  species  named 
in  the  first  list  were  observed  by  Daubree  in  the  veins  near 
Arendal,  and  to  these  he  adds  axinite,  gadolinite,  and  more 
rarely  beryl  and  leucite ;  *  while  in  the  island  of  Utoe,  asso- 
ciated with  iron-ores,  crystalline  limestones,  and  hornblendic 
rocks  passing  into  gneiss,  are  similar  granitic  vein-stones  con- 
taining orthoclase  and  quartz,  with  tourmaline,  cassiterite,  and, 
in  the  middle  of  the  veins,  petalite,  spodumene,  and  lepidolite. 
This  association  is  the  more  worthy  of  notice,  as  the  only  other 
known  locality  of  petalite  (if  we  except  the  castor  of  Elba)  is 
in  the  crystalline  limestone  of  Bolton,  Massachusetts,  where  it 
occurs,  probably  in  a  vein-stone,  with  scapolite,  hornblende, 
pyroxene,  chrysolite,  spinel,  apatite,  and  sphene. 

*  For  a  notice  of  the  occurrence  of  leucite  in  these  veins,  and  also  in  veins  in 
Mexico,  see  the  author's  Contributions  to  Lithology  (Anier.  Journal  Science, 
(2),  XXXVII.  264).  According  to  Garrigou,  this  rare  species  occurs  both  well 
crystallized  and  in  compact  porphyroid  masses,  in  dioritic  rocks  (ophites),  at 
Lusbe  in  the  valley  of  Aspe,  in  the  Pyrenuees.  (Bull.  Soc.  Geol.  de  Fr.  (2), 
XXV.  727.) 


XL]  GRANITES  AND   GRANITIC  VEIN-STONES.  211 

§  39.  Evidences  of  the  concretionary  origin  of  these  granitic 
vein-stones  of  the  Laurentian  rocks  appear  in  their  banded 
structure,  their  drusy  cavities,  the  peculiar  incrustations  and 
modes  of  enclosure  often  observed  in  the  crystals,  and  finally 
in  the  rounded  forms  of  certain  crystals,  which  show  a  process 
of  partial  solution  succeeding  that  of  deposition.  A  banded 
arrangement  of  the  materials  parallel  to  the  sides  of  the  vein  is 
often  well  marked.  Thus,  while  the  walls  may  be  coated  with 
crystalline  hornblende,  or  with  phlogopite,  the  body  of  the  vein 
will  be  filled  with  apatite,  in  the  midst  of  which  may  be  found 
a  mass  of  loganite,  or  of  crystalline  orthoclase  mixed  with  quartz, 
filling  the  centre  of  the  vein,  as  already  noticed  in  §  36.  In 
other  instances  portions  of  the  vein  will  be  occupied  by  crystals 
of  apatite,  pyroxene,  or  phlogopite  imbedded  in  calcareous  spar, 
which  in  some  other  part  of  the  breadth  of  the  vein,  or  in  its 
prolongation,  will  so  far  predominate  as  to  give  to  the  mass  the 
aspect  of  a  coarsely  crystalline  lamellar  limestone.  Prisms  of 
apatite  are  often  observed  extending  from  either  side  toward 
the  centre  of  the  vein,  which  in  some  cases  may  be  filled  with 
calcite  or  another  mineral,  and  in  others  is  a  vacant  space  lined 
with  crystals.  Drusy  cavities  of  this  kind,  a  foot  in  breadth 
and  several  feet  in  length  and  depth,  are  sometimes  met  with 
in  these  veins  in  Ontario. 

§  40.  Further  evidence  of  concretionary  origin  is  seen  in  the 
manner  in  which  the  various  minerals  incrust  each  other.  Thus 
small  prisms  of  apatite  are  enclosed  in  large  crystals  of  phlo- 
gopite, in  pyroxene,  in  quartz,  and  even  in  massive  apatite ; 
crystals  or  rounded  crystalline  masses  of  calcite  are  imbedded 
in  apatite  and  in  quartz,  and  well-defined  crystals  of  hornblende 
(pargasite)  in  pyroxene.  In  another  example  before  me,  small 
crystals  of  hornblende  are  implanted  on  a  large  crystal  of 
pyroxene,  and  both,  in  their  turn,  are  incrusted  by  small  crys- 
tals of  epidote.  Crystalline  graphite  in  like  manner  is  enclosed 
alike  in  orthoclase,  quartz,  calcite,  phlogopite,  and  pyroxene. 

§  41.  Another  noticeable  evidence  of  the  concretionary  origin 
of  these  veins  is  the  phenomenon  already  referred  to  in  §  25, 
where  the  external  skeleton  or  framework  of  a  crystal  is  com- 


212  GRANITES  AND  GRANITIC  VEIN-STONES.  [XI. 

plete,  while  the  space  within  either  remains  empty,  or  is  filled 
with  other  minerals,  often  unsyinmetrically  arranged.  This 
condition  of  things  is  rendered  intelligible  by  the  forma- 
tion of  similar  hollow  crystals  during  the  cooling  of  certain 
saline  solutions,  as  for  example  potash-nitrate.  Small  hollow 
prisms  of  red  and  green  tourmaline,  closely  resembling  the 
hollow  nitre  crystals,  are  common  in  the  well-known  gra- 
nitic vein-stone  of  Paris,  Maine.  I  have  elsewhere  referred 
to  the  formation  of  such  moulds  or  skeleton-crystals  as  having 
taken  place  in  vein-cavities,  and  as  serving  to  explain  many 
cases  of  enclosure  of  mineral  species.  (Address  to  the  A.  A.  A. 
S.,  Indianapolis,  1871.  Paper  XIII.  of  the  present  volume.) 
In  addition  to  the  examples  there  cited,  the  Laurentian  vein- 
stones afford  some  curious  cases.  Thus  a  prism  of  yellow 
idocrase  half  an  inch  in  diameter  from  a  vein  in  Grenville, 
Ontario,  composed  chiefly  of  orthoclase  and  pyroxene,  is  seen 
when  broken  across  to  consist  of  a  thin  shell  of  idocrase  filled 
with  a  confused  crystalline  aggregate  of  orthoclase,  which 
encloses  a  small  crystal  of  zircon.  In  like  manner  large  crys- 
tals of  zircon  from  similar  veins  in  St.  Lawrence  County,  New 
York,  are  sometimes  shells  filled  with  calcite. 

§  42.  The  rounded  forms  of  certain  crystals  in  the  Lauren- 
tian vein-stones  were,  I  believe,  first  noticed  by  Emmons,  who 
observed  that  crystals  of  quartz  imbedded  in  carbonate  of  lime 
from  Eossie,  New  York,  have  their  angles  so  much  rounded 
that  the  crystalline  form  is  nearly  or  quite  effaced,  the  surfaces 
being  at  the  same  time  smooth  and  shining.  This  appearance 
is  occasionally  observed  in  other  localities,  and  is  not  confined 
to  quartz  alone,  crystals  of  calcite  and  of  apatite  sometimes 
exhibiting  the  same  peculiarity.  At  the  same  time  the  ortho- 
clase, scapolite,  pyroxene,  and  zircon,  which  are  associated  with 
these  rounded  crystals,  preserve  all  their  sharpness  of  outline, 
as  was  observed  by  Emmons  for  the  orthoclase  in  contact 
with  the  crystals  of  quartz  just  described.  He  suggested  that 
the  rounded  outlines  of  these  crystals  were  due  to  a  partial 
fusion,  although  he  did  not  overlook  a  fact  which  renders 
this  explanation  untenable,  namely,  that  the  species  presenting 


XI.]  GRANITES  AND  GRANITIC  VEIN-STONES.  213 

rounded  angles  are  much  less  fusible  than  those  which,  in 
contact  with  them,  preserve  their  crystalline  forms  intact. 
(Geology  of  the  First  District  of  New  York,  pages  57,  58.) 
These  facts  are  well  shown  in  the  apatite-veins  of  Elmsley  and 
Burgess,  Ontario,  where  the  crystals  of  apatite  rarely  present 
sharp  or  well-defined  forms,  but  (whether  lining  drusy  cavities 
or  imbedded  in  the  calcite  or  other  minerals  of  the  vein-stone) 
are  most  frequently  rounded  or  sub-cylindrical  masses,  while 
the  pyroxene  and  sphene,  which  often  accompany  them,  pre- 
serve their  distinctness  of  form.  This  rounding  of  the  angles 
of  certain  crystals  appears  to  me  nothing  more  than  a  result  of 
the  solvent  action  of  the  heated  watery  solutions  from  which 
the  minerals  of  these  veins  were  deposited ;  the  crystals  pre- 
viously formed  being  partially  redissolved  by  some  change  in 
the  temperature  or  the  chemical  constitution  of  the  solution. 
Heated  solutions  of  alkaline  silicate,  as  shown  by  Daubree, 
are  without  action  on  feldspar,  as  might  be  expected  from  the 
fact  observed  by  him  of  the  production  of  crystals  of  feldspar, 
as  well  as  of  pyroxene,  in  the  midst  of  such  solutions.  These 
liquids  would,  however,  doubtless  attack  and  dissolve  apatite, 
which  is  in  like  manner  decomposed  by  solutions  of  alkaline 
carbonate,  and  these  latter  at  elevated  temperatures  dissolve 
crystallized  quartz.  That  this  solvent  process  has  been  re- 
peated during  the  filling  of  the  veins  is  seen  by  a  specimen 
in  my  possession,  which  shows  crystals  of  calcite  previously 
rounded  and  enclosed  in  a  large  crystal  of  quartz,  the  angles 
of  which  are  also  nearly  obliterated.  From  the  alternations  in 
the  deposited  mineral  matters  in  many  vein-stones,  as  well  as 
from  what  we  know  of  the  changing  composition  of  mineral 
springs,  it  is  evident  that  the  waters  circulating  in  the  fissures 
now  occupied  by  veins  must  have  been  subject  to  periodical 
variations  in  composition. 

§  43.  In  the  Geology  of  Canada  (page  729)  I  have  noticed 
an  example  of  rounded  quartz  crystals  in  the  veins  at  the 
Harvey  Hill  copper-mine  in  Leeds,  Quebec.  Large  terminated 
prisms  of  limpid  colorless  quartz  are  there  found  imbedded 
in  compact  erubescite,  their  angles  being  much  rounded,  while 


214  GRANITES  AND   GRANITIC  VEIN-STONES.  [XL 

their  faces  are  concave,  and  have  lost  their  polish,  retaining 
only  a  somewhat  greasy  lustre.  A  thin  shining  green  layer, 
apparently  of  a  silicate  of  copper,  covers  the  surfaces  of  the  ore 
in  contact  with  the  crystals.  From  the  mode  of  their  arrange- 
ment in  certain  specimens,  it  is  evident  that  these  prisms  of 
quartz,  lining  drusy  cavities,  were  partially  dissolved  previous 
to  the  deposition  of  the  metallic  sulphide. 

§  44.  Some  of  the  more  important  types  of  Laurentian 
vein-stones  may  now  be  noticed.  Those  made  up  of  quartz 
with  orthoclase,  muscovite,  and  black  tourmaline,  often  with 
zircon,  are  not  unfrequent  in  the  Laurentian  gneiss,  though  so 
far  as  yet  observed  less  abundant  than  in  the  gneisses  and 
mica-schists  of  the  White  Mountain  series.  It  is  true,  as 
already  pointed  out,  that,  from  the  greater  softness  of  the  en- 
closing rocks,  the  veins  of  the  latter  series  are  often  weathered 
into  relief  (§  20),  and  are  thus  rendered  more  conspicuous 
than  those  in  the  harder  Laurentian  gneisses.  Among  other 
examples  of  this  first  type  of  granitic  veins  may  be  mentioned 
those  in  Yeo's  Island  among  the  Thousand  Isles  of  the  St. 
Lawrence,  and  the  well-known  vein  in  Greenfield,  near  Sam- 
toga,  remarkable  for  affording  crystals  of  chrysoberyl.  A  fre- 
quent type  among  the  Laurentian  granitic  veins  is  characterized 
by  great  cleavable  masses  of  reddish  or  reddish-brown  orthoclase, 
with  quartz  and  but  little  mica.  With  these  are  sometimes 
associated  equally  large  masses  of  white  or  pale-colored  albite  ; 
these  veins  are  sometimes  of  great  size,  one  hundred  feet  or 
more  in  breadth.  The  perthite  of  Thompson,  well  known  as  a 
cleavable  feldspar  made  up  of  alternate  thin  plates  of  reddish- 
brown  orthoclase  and  white  albite,  forms  with  quartz  a  large 
granitic  vein ;  while  the  peristerite  of  the  same  author  is  an 
opalescent  or  chatoyant  white  albite,  with  blue  and  green  re- 
flections, which  occurs  with  quartz  in  another  vein  in  the  same 
region.  Some  of  the  veins  of  red  orthoclase  include  large 
cleavable  masses  of  dark  green  hornblende,  occasionally  with 
magnetite.  A  remarkable  vein  about  eighty  feet  in  width,  in 
Buckingham,  Quebec,  is  composed  entirely  of  reddish-white 
orthoclase  and  cleavable  magnetite,  the  latter  in  masses  some- 


XL]  GRANITES  AND   GRANITIC  VEIN-STONES.  215 

times  two  or  three  inches  in  diameter,  scattered  through  the 
feldspar. 

§  45.  The  veins  hitherto  noticed  occur  in  gneiss,  but  on  the 
river  Rouge  one  consisting  of  large  masses  of  quartz  and  albite 
is  found  in  crystalline  limestone.  A  remarkable  vein  described 
by  Sir  William  Logan  in  Blythefield,  Ontario,  traverses  alter- 
nate strata  of  limestone  and  gneiss,  and  has  a  breadth  of  not 
less  than  150  feet.  It  consists  in  great  part  of  a  coarsely 
cleavable  pale  green  pyroxene  (sahlite),  with  a  dark  green 
hornblende,  phlogopite,  and  calcite.  Portions  of  the  vein-stone, 
however,  consist  of  an  admixture  of  orthoclase,  quartz,  and 
black  tourmaline,  showing  the  transition  from  the  calcareous  to 
the  feldspathic  type  of  veins.  In  Ross,  Ontario,  a  vein  holds 
large  isolated  crystals  of  white  orthoclase  imbedded  with  black 
spinel,  apatite,  and  fluorite  in  a  base  of  lamellar  pink  carbonate 
of  lime.  One  of  the  most  remarkable  of  these  composite  veins 
is  in  Grenville,  Quebec,  and  was  formerly  worked  for  graphite. 
It  cuts  a  crystalline  limestone,  itself  holding  graphite  and 
phlogopite,  and  has  afforded  not  less  than  fourteen  distinct 
mineral  species,  namely,  calcite,  apatite,  serpentine,  wollastonite, 
pyroxene,  scapolite,  orthoclase,  oligoclase,  garnet,  idocrase,  zircon, 
quartz,  sphene,  and  graphite.  An  adjacent  vein  abounds  in  phlo- 
gopite, with  pyroxene  and  zircon.  A  not  less  remarkable  vein 
is  that  described  by  Blake  in  Vernon,  New  Jersey  (this  Journal 
(2),  XIII.  116),  in  which  calcite,  fluorite,  chondrodite,  phlogo- 
pite, margarite,  spinel,  corundum,  zircon,  sphene,  rutile,  menacca- 
nite,  pyrite,  and  graphite  occur.  Some  of  these  contain  bary- 
tine,  and  in  one  case  I  have  observed  natrolite,  both  seemingly 
rilling  cavities,  and  of  later  origin  than  the  other  minerals. 
The  remarkable  zinciferous  minerals,  franklinite,  ziucite,  dys- 
luite,  and  willemite,  found  in  the  Laurentian  limestones  of 
New  Jersey,  appear  from  the  descriptions  of  H.  D.  Rogers  to 
belong  to  calcareous  vein-stones.  Granitic  veins  are  found 
traversing  the  magnetic  iron  ore-beds  of  the  Laurentian  series. 
I  have  described  one  in  Moriah,  New  York,  which  includes 
angular  fragments  of  the  magnetite  which  forms  its  walls,  and 
consists  of  a  cleavable  greenish  triclinic  feldspar,  with  quartz 


216  GRANITES  AND   GRANITIC  VEIN-STONES.  [XI. 

crystals  having  rounded  angles,  octahedrons  of  magnite,  al- 
lanite,  and  a  soft  greenish  mineral  resembling  loganite. 

§  46.  As  regards  the  order  of  deposition  of  minerals  in 
these  veins,  we  find  apatite  enclosed  alike  in  calcite,  in  quartz, 
in  phlogopite,  in  spinel,  in  graphite,  and  in  pyrite.  On  the 
other  hand,  apatite  sometimes  includes  rounded  crystals  of 
calcite  or  of  quartz ;  and  graphite,  which  itself  encloses  apatite, 
is  found  included  alike  in  quartz,  in  orthoclase,  in  pyroxene, 
and  in  calcite,  in  such  a  manner  as  to  lead  us  to  conclude  that 
its  crystallization  was  contemporaneous  with  that  of  all  these 
minerals ;  while  from  the  other  facts  mentioned  it  would  appear 
that  the  order  of  deposition  was  subject  to  variation  and  to 
alternations.  In  a  vein  in  Grenville  large  prisms  of  a  white 
aluminous  pyroxene  (leucaugite)  penetrate  great  crystals  of 
phlogopite,  while  at  the  same  time  small  crystals  of  a  similar 
mica  are  completely  imbedded  in  the  crystallized  pyroxene. 
Many  facts  relating  to  the  association  of  various  species  in 
these  vein-stones  will  be  found  in  my  essay,  but  the  subject  is 
one  which  still  demands  careful  study.  The  banded  structure 
of  these  veins  is  well  shown  in  some  of  those  which  contain 
graphite.  This  mineral,  though  sometimes  irregularly  dissemi- 
nated through  the*  vein-stone,  frequently  occurs  in  sheets  or 
layers  alternating  with  orthoclase,  quartz,  or  pyroxene,  parallel 
to  the  walls  of  the  vein  and  exhibiting  a  peculiar  structure  due 
to  the  formation  of  successive  layers  of  crystalline  lamellee 
more  or  less  nearly  perpendicular  to  the  plane  of  deposition. 

§  47.  The  veins  hitherto  noticed,  .whether  feldspathic  or 
calcareous,  are  generally  vertical,  or  nearly  so,  and  in  most 
cases  traverse  the  stratification.  Of  many  of  them  which  have 
been  explored  to  some  extent  for  apatite,  mica,  and  graphite,  it 
is  noticed  that  they  are  subject  to  great  changes  in  dimension 
as  well  as  in  mineral  contents.  They  often  appear  to  occupy 
short  irregular  fissures,  and  in  some  cases  are  to  be  described 
as  more  or  less  completely  filled  geode-like  cavities  rather  than 
veins. 

§  48.  In  the  reprint  of  my  essay,  already  mentioned,  several 
veins  are  noticed  in  the  county  of  Hastings,  Ontario,  in  rocks 


XL]  GRANITES   AND   GRANITIC  VEIN-STONES.  217 

which  were  at  that  time  referred  by  the  Geological  Survey 
of  Canada  to  the  Laurentian,  but  have  since  been  found  to 
belong  to  younger  series.  Such  are  the  veins  containing  argen- 
tiferous fahlerz  with  mispickel,  and  that  holding  native  gold 
with  a  quasi-anthracitic  form  of  carbon,  both  from  Madoc,  and 
also  the  vein  already  noticed  as  occurring  in  the  township  of 
Lake  (§  36),  which  contains  in  one  part  bismuthine  with  tour- 
maline, quartz,  and  graphite,  and  in  another  part  calcite  with 
phlogopite.  This  latter  vein  occurs  in  an  impure  limestone, 
associated  with  quartzite  and  micaceous  schists,  and  belonging 
to  a  series  unconformably  overlying  the  Laurentian,  and  re- 
sembling the  rocks  of  the  White  Mountain  series.  It  will  be 
noticed  that  this  vein  is  lithologically  similar  to  those  of  the 
Laurentian,  which  are  not  improbably  of  the  same  age.  Cal- 
careous vein-stones  like  those  already  described  are  .not  un- 
known in  the  White  Mountain  rocks  in  Maine,  where  are 
found,  on  a  small  scale,  aggregates  of  crystallized  pyroxene, 
idocrase,  and  sphene,  and  others  of  calcite  with  hornblende, 
apatite,  and  graphite  (§  18),  closely  resembling  the  Laurentiau 
vein-stones  of  New  York  and  Canada.* 

§  49.  The  various  minerals  of  these  calcareous  vein-stones  are 

[*  In  a  note  in  the  American  Journal  of  Science  for  October,  1873,  on  The 
Copper  Deposits  of  the  Blue  Ridge,  I  have  described  the  occurrence  in  Vir- 
ginia, North  Carolina,  and  Tennessee  of  great  concretionary  veins  in  gneisses 
and  mica-schists  which  I  refer  to  the  White  Mountain  series.  These  veins 
are  sometimes  transverse  to  the  stratification,  and  at  other  times  inter- 
bedded.  An  example  of  the  latter  is  seen  at  the  Ducktown  copper- mine  in 
Polk  County,  Tennessee,  where  there  is  a  banded  arrangement  of  the  large 
masses  parallel  to  the  walls.  The  chief  part  of  this  vein  is  filled  with  pyrite, 
pyrrhotine,  and  chalcopyrite,  rarely  with  galena,  blende,  mispickel,  and 
molybdenite.  These  massive  ores  enclose  large  garnets,  and  are  penetrated 
with  prisms  of  zoisite,  hornblende,  and  pyroxene,  sometimes  several  inches  in 
length.  The  hornblende  crystals  are  bent  and  sometimes  partially  broken 
across,  the  transverse  fissures  being  filled  with  sulphurets,  which  are  also 
found  between  the  cleavage  planes  of  large  pyroxene  crystals.  Other  portions 
of  the  vein  are  of  vitreous  quartz,  holding  metallic  sulphides  and  rarely  gar- 
nets, while  large  masses  of  white  cleavable  pyroxene,  and  others  of  finely 
fibrous  greenish  or  white  hornblende,  occur,  besides  masses  of  white  cleava- 
ble calcite  enclosing  long  prisms  of  green  hornblende.  This  vein,  with 
the  exception  of  the  abundance  of  metallic  sulphurets,  resembles  closely  in 
its  contents  the  calcareous  veins  of  the  Laureutian  rocks  above  described.] 
10 


218  GRANITES  AND  GRANITIC  VEIN-STONES.  [XL 

generally  described  as  occurring  in  crystalline  limestones, 
though  C.  U.  Shepard,  H.  D.  Rogers,  and  W.  P.  Blake  have 
each  recognized  the  fact  that  these  mineral  species,  with  their 
calcareous  gangue,  belong  to  true  veins.  Emmons,  however, 
failed  to  distinguish  between  these  vein-stones  and  the  stratified 
limestones  of  the  series,  which,  as  already  stated,  often  contain 
disseminated  many  of  the  same  species,  though  in  a  less  per- 
fectly crystallized  condition  than  in  the  vein-stones.  Since  the 
latter  are  clearly  seen  to  traverse  the  gneiss,  like  dikes,  Emmons 
was  led  to  look  upon  them  as  eruptive  ;  and,  generalizing  from 
this,  he  declared  that  all  the  crystalline  limestones  of  northern 
New  York  were  non-stratified  rocks  of  eruptive  origin.  (Geology 
of  the  First  District  of  New  York,  1842,  pages  37  -  59.)  This 
view  of  Emmons  was,  to  a  certain  extent,  adopted  by  Mather, 
who,  while  maintaining  the  stratified  character  of  the  crystalline 
limestones  of  southern  New  York,  admitted  the  existence  of 
eruptive  limestones.  Yon  Leonhard  had  already,  in  1833, 
asserted  that  limestones  have  sometimes  come  from  the  interior 
of  the  earth  in  a  liquid  state,  like  other  igneous  rocks,  and  a 
similar  view  was  at  that  time  maintained  by  many  other 
geologists.  Among  others  we  find  Rozet  asserting  the  eruptive 
origin  of  the  crystalline  limestones  which  are  associated  with 
gneiss  in  the  mountains  of  the  Vosges.  (Bull.  Soc.  Geol.  de 
France,  III.  215-235.)  In  support  of  this  view  could  be 
urged  the  dike-like  form  of  the  calcareous  vein-stones,  which 
other  observers,  like  Emmons,  confounded  with  the  bedded 
limestones.  The  nature  and  origin  of  this  misconception  were, 
I  believe,  first  pointed  out  by  me  in  a  communication  to  the 
American  Association  for  the  Advancement  of  Science  in  Au- 
gust, 1866  (Canadian  Naturalist  (2),  III.  123),  and  subse- 
quently more  at  length  in  the  essay  so  often  referred  to.  (Report 
Geol.  Survey  of  Canada,  1863-66,  p.  182.)  It  was  there 
shown  that  many  of  these  calcareous  vein-stones  are  nearly  free 
from  foreign  minerals,  and  so  closely  resemble  in  lithological 
characters  the  stratified  limestones,  that  the  different  geognosti- 
cal  relations  of  the  two  alone  enable  us,  in  some  examples,  to 
distinguish  between  them.  In  this  connection  I  called  atten- 


XL]  GRANITES  AND   GRANITIC  VEIN-STONES.  219 

tion  to  the  great  dikes  of  granular  limestones  found  traversing 
gneiss  near  Auerbach  in  the  Bergstrasse,  which  Bischof  has 
described  as  true  vein-stones.  These  endogenous  concretionary 
limestones  are  in  fact  to  stratified  limestones  what  endogenous 
granitic  veins  are  to  gneiss  rocks. 


xn. 

THE   ORIGIN  OF  METALLIFEROUS 
DEPOSITS. 

This  paper,  unlike  the  others  in  this  collection  (with  the  exception  of  IV.),  was  a 
lecture  to  a  general  audience,  given  before  the  American  Institute  of  New  York,  in 
May,  1872,  and  reported  for  their  Proceedings.  It  is  reprinted  here  because  it  states, 
though  in  a  familiar  manner,  certain  views  which  the  author  believes  to  be  important. 
The  following  extract  from  a  review  of  American  Geology  in  the  American  Journal 
of  Science  for  May,  1861  (a  part  of  which  is  published  as  Essay  V.  of  this  volume),  is 
prefixed  as  a  concise  statement  of  some  of  the  points  in  the  lecture. 

"  THE  metals  ....  seem  to  have  been  originally  brought 
to  the  surface  in  watery  solutions,  from  which  we  conceive 
them  to  have  been  separated  by  the  reducing  agency  of  organic 
matters  in  the  form  of  sulphurets  or  in  the  native  state,  and 
mingled  with  the  contemporaneous  sediments,  where  they  occur 
in  beds,  in  disseminated  grains  forming  fahlbands,  or  are  the 
cementing  material  of  conglomerates.  During  the  subsequent 
metamorphism  of  the  strata  these  metallic  matters,  being  taken 
into  solution  by  alkaline  carbonates  or  sulphurets,  have  been 
redeposited  in  fissures  in  the  metalliferous  strata,  forming  veins, 
or,  ascending  to  higher  beds,  have  given  rise  to  metalliferous 
veins  in  strata  not  themselves  metalliferous.  Such  we  conceive 
to  be,  in  a  few  words,  the  theory  of  metallic  deposits ;  they 
belong  to  a  period  when  the  primal  sediments  were  yet  impreg- 
nated with  metallic  compounds  which  were  soluble  in  the  per- 
meating waters.  The  metals  of  the  sedimentary  rocks  are  now, 
however,  for  the  greater  part  in  the  form  of  insoluble  sulphurets, 
so  that  we  have  only  traces  of  them  in  a  few  mineral  springs, 
which  serve  to  show  the  agencies  once  at  work  in  the  sedi- 
ments and  waters  of  the  earth's  crust.  The  present  occurrence 
of  these  metals  in  waters  which  are  alkaline  from  the  presence 


XII.]  ORIGIN  OF  METALLIFEROUS  DEPOSITS.  221 

of  carbonate  of  soda,  is  of  great  significance  when  taken  in 
connection  with  the  metalliferous  character  of  certain  dolomites, 
which,  as  we  have  shown,  probably  owe  their  origin  to  the 
action  of  similar  alkaline  springs  upon  basins  of  sea-water." 
(Ante,  page  88.) 

"  The  intervention  of  intense  heat,  sublimation,  and  similar 
hypotheses  to  explain  the  origin  of  metallic  ores,  we  conceive 
to  be  uncalled  for.  The  solvent  powers  of  solutions  of  alkaline 
carbonates,  chlorides,  and  sulphurets  at  elevated  temperatures, 
taken  in  connection  with  the  notions  above  enunciated,  and 
with  De  Senarmont's  and  Daubree's  beautiful  experiments  on 
the  crystallization  of  certain  mineral  species  in  the  moist  way, 
will  suffice  to  form  the  basis  of  a  satisfactory  theory  of  metallic 
deposits."  (Ante,  page  25.) 

There  are  about  sixty  bodies  which  chemists  call  elements ; 
the  simplest  forms  of  matter  which  they  have  been  able  to 
extract  from  the  rocky  crust  of  our  earth,  its  waters,  and  its 
atmosphere.  These  substances  are  distributed  in  very  unequal 
quantities,  and  in  very  different  manners.  As  regards  the  fre- 
quency of  these  elements  in  nature,  neglecting  for  the  present 
those  which  constitute  air  and  water,  and  confining  ourselves  to 
the  solid  matters  of  the  earth's  crust,  there  are  a  few  which  are 
exceedingly  abundant,  making  up  nine  tenths,  if  not  ninety-five 
hundredths,  of  the  rocks  so  far  as  known  to  us.  The  elements 
of  which  silica,  alumina,  lime,  magnesia,  potash,  and  soda  are 
oxides  are  very  common,  and  occur  almost  everywhere.  There 
are  others  which  are  much  rarer,  being  found  in  comparatively 
small  quantities.  Many  of  these  rarer  elements  are,  however, 
of  great  importance  in  the  economy  of  nature.  Such  are  the 
common  metals  and  other  substances  used  in  the  arts,  which 
occur  in  nature  in  quantities  relatively  very  minute,  but  which 
have  been  collected  by  various  agencies,  and  thus  made  available 
for  the  wants  of  man.  It  is  chiefly  of  the  well-known  metals, 
iron,  copper,  silver,  and  gold,  that  I  propose  to  speak ;  but 
there  are  two  other  elements,  not  classed  among  the  metals, 
which  I  shall  notice  for  the  reason  that  their  history  is  ex- 
tremely important,  and  will,  moreover,  enable  us  to  comprehend 


222  ORIGIN   OF  METALLIFEROUS  DEPOSITS.  [XII. 

more  clearly  some  points  in  that  of  the  metals  themselves.  I 
speak  of  phosphorus  and  iodine. 

You  all  know  the  essential  part  which  the  former  of  these, 
combined  as  phosphate  of  lime,  plays  in  the  animal  economy, 
in  the  formation  of  bones ;  and  how  plants  require  for  their 
proper  growth  and  development  a  certain  amount  of  phos- 
phorus. Ordinary  soils  contain  only  a  few  thousandths  of  this 
element,  yet  there  are  agencies  at  work  in  nature  which  gather 
this  diffused  phosphorus  together  in  beds  of  mineral  phosphates 
and  in  veins  of  crystalline  apatite,  which  are  now  sought  to 
enrich  impoverished  soils.  Iodine,  an  element  of  great  value 
in  medicine  and  in  the  art  of  photography,  is  widely  distributed, 
but  still  rarer  than  phosphorus  ;  yet  it  abounds  in  certain  min- 
eral waters,  and  is,  moreover,  accumulated  in  marine  plants. 
These  extract  it  from  the  waters  of  the  sea,  where  iodine  exists 
in  such  minute  quantities  as  almost  to  elude  our  chemical 
tests.  (See  the  Appendix,  page  237.) 

There  are  probably  no  perfect  separations  in  nature.  "We 
cannot,  without  great  precautions,  get  any  chemical  element 
in  a  state  of  absolute  purity,  and  we  have  reason  to  believe 
that  even  the  rarest  elements  are  everywhere  diffused  in  infini- 
tesimal quantities.  The  spectroscope,  which  we  have  lately 
learned  to  apply  to  the  investigation  alike  of  the  chemistry  of 
our  own  earth  and  of  other  worlds  once  supposed  to  be  beyond 
the  chemist's  ken,  not  only  demonstrates  the  very  wide  diffu- 
sion of  various  chemical  elements  here  on  the  earth,  but  shows 
us  that  very  many  of  them  exist  in  the  sun.  If  we  accept,  as 
most  of  us  are  now  inclined  to  do,  the  nebular  hypothesis,  and 
admit  that  our  earth  was  once,  like  the  sun  of  to-day,  an  in- 
tensely heated  vaporous  mass  ;  that  it  is,  in  fact,  a  cooled  and 
condensed  portion  of  that  once  great  nebula  of  which  the  sun 
is  also  a  part,  —  we  might  expect  to  find  all  the  elements  now 
discovered  in  the  sun  distributed  throughout  this  consolidated 
globe.  We  may  speculate  about  the  condensation  of  some  of 
these  before  others,  and  their  consequent  accumulation  in  the 
inner  parts  of  the  earth ;  but  the  fact  that  we  have  all  the  ele- 
ments of  the  solar  envelope  (together  with  many  more)  in  the 


XII.]  ORIGIN   OF  METALLIFEROUS  DEPOSITS.  223 

exterior  portions  of  our  planet,  shows  that  there  was,  at  least, 
but  a  very  partial  concentration  and  separation  of  these  ele- 
ments during  the  period  of  cooling  and  condensation.  The 
superficial  crust  of  the  earth,  from  which  all  the  rocks  and 
minerals  which  we  know  have  been  generated,  must  have 
contained,  diffused  through  it,  from  the  earliest  time,  all  the 
elements  which  we  now  meet  with  in  our  study  of  the  earth, 
whether  still  diffused,  or  accumulated,  as  we  often  find  the 
rarer  elements,  in  particular  veins  or  beds. 

The  question  now  before  us  is,  How  have  these  elements 
thus  been  brought  together,  and  why  is  it  that  they  are  not  all 
still  widely  and  universally  diffused  ?  Why  are  the  compounds 
of  iron  in  beds  by  themselves,  copper,  silver,  and  gold  gathered 
together  in  veins,  and  iodine  concentrated  in  a  few  ores  and 
certain  mineral  waters  ?  That  we  may  the  better  discern  the 
direction  in  which  we  are  to  look  for  the  solution  of  this 
problem,  let  us  premise  that  all  of  these  elements,  in  some  of 
their  combinations,  are  more  or  less  soluble  in  water.  There 
are,  in  fact,  no  such  things  in  nature  as  absolutely  insoluble 
bodies,  but  all,  under  certain  conditions,  are  capable  of  being 
taken  up  by  water,  and  again  deposited  from  it.*  The  al- 
chemists sought  in  vain  for  a  universal  solvent ;  but  we  now 
know  that  water,  aided  in  some  cases  by  heat,  pressure,  and 
the  presence  of  certain  widely  distributed  substances,  such  as 
carbonic  acid  and  alkaline  carbonates  and  sulphides,  will  dis- 
solve the  most  insoluble  bodies ;  so  that  it  may,  after  all,  be 
looked  upon  as  the  long-sought-for  alkahest  or  universal  men- 
struum. 

[*  It  is  well  known  that  many  chemical  compounds  when  first  generated  by 
double  Decomposition  in  watery  solutions  remain  dissolved  for  a  greater  or 
leas  length  of  time  before  separating  in  an  insoluble  condition.  The  solubility 
of  recently  precipitated  carbonate  of  lime  in  water  holding  certain  neutral 
salts,  as  already  described  (ante,  page  140),  is  a  fact  in  the  same  order.  In  this 
connection  may  also  be  recalled  the  great  solubility  in  water  of  silicic,  titanic, 
stannic,  ferric,  aluminic,  and  chromic  oxides  when  in  what  Graham  has 
called  their  colloidal  state.  There  is  reason  to  believe  that  silicates  of  in- 
soluble bases  may  assume  a  similar  state,  and  it  will  probably  one  day  be 
shown  that  for  the  greater  number  of  those  oxygenized  compounds  which  we 
call  insoluble  there  exists  a  modification  soluble  in  water.] 


224  ORIGIN  OF  METALLIFEROUS  DEPOSITS.  [XII. 

Let  us  now  compare  the  waters  of  rivers,  seas,  and  subter- 
ranean springs,  thus  impregnated  with  various  chemical  ele- 
ments, with  the  blood  which  circulates  through  our  own  bodies. 
The  analysis  of  the  blood  shows  it  to  contain  albuminoids 
which  go  to  form  muscle,  fat  for  the  adipose  tissues,  phosphate 
of  lime  for  the  bones,  fluorides  for  the  enamel  of  the  teeth, 
sulphur,  which  enters  largely  into  the  composition  of  the  hair 
and  nails,  soda  which  accumulates  in  the  bile,  and  potash, 
which  abounds  in  the  flesh-fluid.  All  of  these  are  dissolved  in 
the  blood,  and  the  great  problem  for  the  chemical  physiologist 
is  to  determine  how  the  living  organism  gathers  them  from 
this  complex  fluid,  depositing  them  here  and  there,  and  giving 
to  each  part  its  proper  material.  This  selection  is  generally 
ascribed  to  a  certain  vital  force,  peculiar  to  the  living  body. 
I  shall  not  here  discuss  the  vexed  question  of  the  nature  of 
the  force  which  determines  the  assimilation  from  the  blood 
of  these  various  matters  for  the  needs  of  the  animal  organism, 
further  than  to  say  that  modern  investigations  tend  to  show 
that  it  is  only  a  subtler  kind  of  chemistry,  and  that  the  study 
of  the  nature  and  relation  of  colloids  and  crystalloids,  and  of 
the  phenomena  of  chemical  diffusion,  promises  to  subordinate 
all  these  obscure  physiological  processes  to  chemical  and  physi- 
cal laws. 

Let  us  now  see  how  far  the  comparison  which  we  have  made 
between  the  earth  and  an  animal  organism  will  help  us  to 
understand  the  problem  of  the  distribution  of  minerals  in 
nature ;  how  far  water,  the  universal  solvent,  acting  in  accord- 
ance with  known  chemical  and  physical  laws,  will  cause  the 
separation  of  the  mixed  elements  of  the  earth's  crust,  and  their 
accumulation  in  veins  and  beds  in  the  rocks.  The  subject  is 
one  of  great  importance  to  the  geologist,  who  has  to  consider  the 
genesis  of  the  various  rocks  and  ore-deposits,  and  the  relations, 
which  we  are  only  beginning  to  understand,  between  certain 
metals  and  particular  rocks,  and  between  certain  classes  of  ores 
and  peculiar  mineralogical  and  geological  conditions.  It  is  at 
the  same  time  a  vast  one,  and  I  can  now  only  give  you  a  few 
illustrations  of  the  chemistry  of  the  earth's  crust,  and  of  the 


XII. ]  ORIGIN  OF  METALLIFEROUS  DEPOSITS.  225 

laws  of  the  terrestrial  circulation,  which  I  have  compared  to 
that  of  the  blood  distributing  throughout  the  animal  frame  the 
elements  necessary  for  its  growth.  The  analogy  is  not  alto- 
gether new,  since  a  great  French  geologist,  Elie  de  Beaumont, 
has  already  spoken  of  a  terrestrial  circulation  in  regard  to  cer- 
tain elements  in  the  earth's  crust ;  though  he  has  not,  so  far  as 
I  am  aware,  carried  it  out  to  the  extent  which  I  now  propose 
to  do  in  my  attempt  to  explain  some  of  the  laws  which  have 
presided  over  the  distribution  of  metals  in  the  earth. 

The  chemist  in  his  laboratory  takes  advantage  of  changes 
of  temperature,  and  of  the  action  of  various  solvents  and 
precipitants,  to  separate,  in  the  humid  way,  one  element  from 
another ;  but  to  these  agencies,  in  the  economy  of  nature,  are 
added  others  which  we  have  not  yet  succeeded  in  imitating, 
and  which  are  exerted  only  in  growing  animals  and  plants.  I 
repeat  it ;  I  do  not  wish  to  say  that  these  latter  processes  are 
different  in  kind  from  those  which  we  command  in  our  labora- 
'*  tories,  but  rather  that  these  organisms  control  a  far  finer  and 
more  delicate  chemical  and  physical  apparatus  than  we  have  yet 
invented.  Plants  have  the  power  of  selecting  from  the  media 
in  which  they  live  the  elements  necessary  for  their  support. 
The  growing  oak  and  the  grass  alike  assimilate  from  the  air  and 
water  the  carbon,  hydrogen,  nitrogen,  and  oxygen  which  build 
up  their  tissues,  and  at  the  same  time  take  from  the  soil  a  portion 
of  phosphorus,  which,  though  minute,  is  essential  to  the  vege- 
table growth.  The  acorn  of  the  oak  and  the  grass  alike  be- 
come the  food  of  animals,  and  the  gathered  phosphates  pass 
into  their  bones,  which  are  nearly  pure  phosphate  of  lime.  In 
like  manner  the  phosphates  from  organic  waste  and  decay  find 
their  way  to  the  sea,  and  through  the  agency  of  marine  vege- 
tation become  at  last  the  bony  skeletons  of  fishes.  These  are, 
in  turn,  the  prey  of  carnivorous  birds,  whose  exuviae  form  on 
tropical  islands  beds  of  phosphatic  guano.  A  history  not  dis- 
similar will  explain  the  origin  of  beds  of  coprolites  and  of  some 
other  deposits  of  mineral  phosphates.  [By  whatever  means 
the  phosphates  have  been  first  concentrated,  it  appears  from 
the  recent  studies  of  Sollas  that  the  so-called  coprolites  of  the 
10*  o 


226  ORIGIN   OF   METALLIFEROUS   DEPOSITS.  [XII. 

green-sand  in  England  result  from  a  petrifaction  of  sponges  by 
dissolved  phosphates,  and  similar  observations  have  been  made 
by  Edwards  with  regard  to  the  guano  of  the  Chincha  Islands.] 

But  again,  these  plants  or  these  animals  may  perish  in  the 
sea  and  be  buried  in  its  ooze.  The  phosphates  which  they 
have  gathered  are  not  lost,  but  become  fixed  in  an  insoluble 
form  in  the  clayey  matter ;  and  when,  in  the  revolutions  of 
ages,  these  sea-muds,  hardened  to  rock,  become  dry  land,  and 
crumble  again  to  soil,  the  phosphates  are  there  found  ready  for 
the  wants  of  vegetation. 

Most  of  what  I  have  said  of  phosphates  applies  equally  to 
the  salts  of  potash,  which  are  not  less  necessary  to  the  growing 
plant.  From  the  operation  of  these  laws  it  results  that  neither 
of  these  elements  is  found  in  large  quantities  in  the  ocean. 
This  great  receptacle  of  the  drainage  from  the  land  contains 
still  smaller  quantities  of  iodine ;  in  fact,  the  traces  of  this 
element  present  in  sea-water  can  scarcely  be  detected  by  our 
most  delicate  tests.*  Yet  marine  plants  have  the  power  of 
separating  this  iodine,  and  accumulating  it  in  their  tissues,  so 
that  the  ashes  of  these  plants  are  not  only  rich  in  phosphates 
and  in  potash-salts,  but  contain  so  much  iodine  that  our  sup- 
plies of  this  precious  element  are  almost  wholly  derived  from 
this  source,  and  that  the  gathering  and  burning  of  sea- weed  for 
the  extraction  of  iodine  is  in  some  regions  an  important  indus- 
try. When  this  marine  vegetation  decays,  the  iodine  which  it 
contains  appears,  like  the  potash  and  phosphates,  to  pass  into 
combination  with  metals,  earths,  or  earthy  phosphates,  which 
retain  it  in  an  insoluble  state,  and  in  certain  cases  yield  it  to 
percolating  saline  solutions,  which  thus  give  rise  to  springs 
rich  in  iodine.  (Ante,  page  143.) 

In  all  of  these  processes  the  action  of  organic  life  is  direct 
and  assimilative,  but  there  are  others  in  which  its  agency, 
although  indirect,  is  not  less  important.  I  can  hardly  con- 
ceive of  an  accumulation  of  iron,  copper,  lead,  silver,  or  gold, 
in  the  production  of  which  animal  or  vegetable  life  has  not 
either  directly  or  indirectly  been  necessary,  and  I  shall  be- 
*  See  the  Appendix  to  this  paper. 


XIL]  ORIGIN  OF  METALLIFEROUS  DEPOSITS.  227 

gin  to  explain  my  meaning  by  the  case  of  iron.  This,  you 
are  aware,  is  one  of  the  most  widely  diffused  elements  in 
nature ;  all  soils,  all  plants,  contain  it ;  and  it  is  a  necessary 
element  in  our  blood.  Clays  and  loams  contain,  however,  at 
best,  two  or  three  hundredths  of  the  metal,  but  so  mixed  with 
other  matters  that  we  could  never  make  it  available  for  the 
wants  of  this  iron  age  of  ours.  How  does  it  happen  that  we 
also  find  it  gathered  together  in  great  beds  of  ore,  which  fur- 
nish an  abundant  supply  of  the  metal  ]  The  chemist  knows 
that  the  iron,  'as  diffused  in  the  rocks,  exists  chiefly  in  combi- 
nation with  oxygen,  with  which  it  forms  two  principal  com- 
pounds :  the  first,  or  protoxide,  which  is  readily  soluble  in 
•waters  impregnated  with  carbonic  acid  or  other  feeble  acids; 
and  the  second,  or  peroxide,  which  is  insoluble  in  the  same 
liquids.  I  do  not  here  speak  of  the  magnetic  oxide,  which 
may  be  looked  upon  as  a  compound  of  the  other  two,  neutral 
and  indifferent  to  most  natural  chemical  agencies.  The  com- 
binations of  the  first  oxide  are  either  colorless  or  bluish  or 
greenish  in  tint,  while  the  peroxide  is  reddish-brown,  and  is 
the  substance  known  as  iron-rust.  Ordinary  brick-clays  are 
bluish  in  color,  and  contain  combined  iron  in  the  state  of 
protoxide,  but  when  burned  in  a  kiln  they  become  reddish, 
because  this  oxide  absorbs  from  the  air  a  further  proportion 
of  oxygen,  and  is  converted  into  peroxide.  But  there  are  clays 
which  are  white  when  burned,  and  are  much  prized  for  this 
reason.  Many  of  these  were  once  ferruginous  clays,  which 
have  lost  their  iron  by  a  process  everywhere  going  on  around 
us.  If  we  dig  a  ditch  in  a  moist  soil  which  is  covered  with 
turf  or  with  decaying  vegetation,  we  may  observe  that  the 
stagnant  water  which  collects  at  the  bottom  soon  becomes 
coated  with  a  shining,  iridescent  scum,  which  looks  somewhat 
like  oil,  but  is  really  a  compound  of  peroxide  of  iron.  The 
water  as  it  oozes  from  the  soil  is  colorless,  but  has  an  inky 
taste,  from  dissolved  protoxide  of  iron.  When  exposed  to  the 
air,  however,  this  absorbs  oxygen,  and  the  peroxide  is  formed, 
which  is  no  longer  soluble,  but  separates  as  a  film  on  the  sur- 
iace  of  the  water,  and  finally  sinks  to  the  bottom  as  a  reddish 


228  ORIGIN  OF  METALLIFEROUS  DEPOSITS.  [XII. 

ochre,  or,  under  somewhat  different  conditions,  becomes  aggre- 
gated as  a  massive  iron-ore.  A  process  identical  in  kind  with 
this  has  been  at  work  at  the  earth's  surface  ever  since  there 
were  decaying  organic  matters,  dissolving  the  iron  from  the 
porous  rocks,  clays,  and  sands,  and  gathering  it  together  in 
beds  of  iron-ore  or  iron-ochre.  It  is  not  necessary  that  these 
rocks  and  soils  should  contain  the  iron  in  the  state  of  pro- 
toxide, since  these  organic  products  (which  are  themselves 
dissolved  in  the  water)  are  able  to  remove  a  portion  of  the 
oxygen  from  the  insoluble  peroxide,  and  convert  it  into  the 
soluble  protoxide  of  iron,  being  themselves  in  part  oxidized 
and  converted  into  carbonic  acid  in  the  process. 

We  find  in  rock-formations  of  very  different  ages  beds  of 
sediments  which  have  been  deprived  of  iron  by  organic  agen- 
cies, and  near  them  will  generally  be  found  the  accumulated 
iron.  Go  into  any  coal  region,  and  you  will  see  evidences  that 
this  process  was  at  work  when  the  coal-beds  were  forming. 
The  soil  in  which  the  coal-plants  grew  has  been  deprived  of  its 
iron,  and  when  burned  turns  white,  as  do  most  of  the  slaty 
beds  from  the  coal-rocks.  It  is  this  ancient  soil  which  con- 
stitutes the  so-called  fire-clays,  prized  for  making  bricks  which, 
from  the  absence  of  both  iron  and  alkalies,  are  very  infusible. 
Interstratified  with  these  we  often  find,  in  the  form  of  iron- 
stone, the  separated  metal ;  and  thus  from  the  same  series  of 
rocks  may  be  obtained  the  fuel,  the  ore,  and  the  fire-clay. 

From  what  I  have  said  it  will  be  understood  that  great 
deposits  of  iron-ore  generally  occur  in  the  shape  of  beds ;  al- 
though waters  holding  the  compounds  of  iron  in  solution  have, 
in  some  cases,  deposited  them  in  fissures  or  openings  in  the 
rocks,  thus  forming  true  veins  of  ore,  of  which  we  shall  speak 
further  on.  I  wish  now  to  insist  upon  the  property  which 
dead  and  decaying  organic  matters  possess  of  reducing  to 
protoxide,  and  rendering  soluble,  the  insoluble  peroxide  of  iron 
diffused  through  the  rocks ;  and  reciprocally  the  power  which 
this  peroxide  has  of  oxidizing  and  consuming  these  same 
organic  matters,  which  are  thereby  finally  converted  into  car- 
bonic acid  and  water.  This  last  action,  let  me  say  in  passing, 


XII.]  ORIGIN  OF  METALLIFEROUS  DEPOSITS.  229 

is  illustrated  by  the  destructive  action  of  rusting  iron  bolts 
on  moist  wood,  and  the  effect  of  iron  stains  in  impairing  the 
strength  of  linen  fibre. 

We  see  in  the  coal  formation  that  the  vegetable  matter 
necessary  for  the  production  of  the  iron-ore  beds  was  not 
wanting ;  but  the  question  has  been  asked  me,  Where  are  the 
evidences  of  the  organic  material  which  was  required  to  pro- 
duce the  vast  beds  of  iron-ore  found  in  the  ancient  crystalline 
rocks  1  I  answer  that  the  organic  matter  was,  in  most  cases, 
entirely  consumed  in  producing  these  great  results ;  and  that 
it  was  the  large  proportion  of  iron  diffused  in  the  soils  and 
waters  of  these  early  times,  which  not  only  rendered  possible 
the  accumulation  of  such  great  beds  of  ore,  but  oxidized  and 
destroyed  the  organic  matters  which  in  later  ages  appear  in 
coals,  lignites,  pyroschists,  and  bitumens.  Some  of  the  carbon 
of  these  early  times  is,  however,  still  preserved  in  the  form  of 
graphite,  and  it  would  be  possible  to  calculate  how  much  car- 
bonaceous material  was  consumed  in  the  formation  of  the  great 
iron-ore  beds  of  the  older  rocks,  and  to  determine  of  how  much 
coal  or  lignite  they  are  the  equivalents. 

In  the  course  of  ages,  however,  as  a  large  proportion  of  the 
once  diffused  iron-oxide  has  become  segregated  in  the  form  of 
beds  of  ore,  and  thus  removed  from  the  terrestrial  circulation, 
the  conditions  have  grown  more  favorable  for  the  preservation 
of  the  carbonaceous  products  of  vegetable  life.  The  crystalline 
magnetic  and  specular  oxides,  which  constitute  a  large  propor- 
tion of  the  ores  of  this  metal,  are  almost  or  altogether  indiffer- 
ent to  the  action  of  organic  matter.  When,  however,  these 
ores  are  reduced  in  our  furnaces,  and  the  resulting  metal  is 
exposed  to  the  oxidizing  action  of  a  moist  atmosphere,  it  is 
again  converted  into  iron-rust,  which  is  soluble  in  water  hold- 
ing organic  matters,  and  may  thus  be  made  to  enter  once  more 
into  the  terrestrial  circulation. 

There  is  another  form  in  which  iron  is  frequently  concen- 
trated in  nature,  that  of  sulphide,  and  most  frequently  as  the 
bisulphide,  known  as  iron-pyrites.  This  substance  is  found 
both  in  the  oldest  and  the  newest  rocks,  and,  like  the  oxide  of 


230  OEIGIN   OF   METALLIFEROUS   DEPOSITS.  [XII. 

iron,  is  even  to-day  forming  in-  certain  waters  and  in  beds  of 
mud  and  silt,  where  it  sometimes  takes  a  beautifully  crystalline 
shape.  What  are  the  conditions  in  which  the  sulphide  of 
iron  is  formed  and  deposited,  instead  of  the  oxide  or  carbonate 
of  iron1?  Its  production  depends,  like  these,  on  decaying 
organic  matters.  The  sulphates  of  lime  and  magnesia,  which 
abound  in  sea-water,  and  in  many  other  natural  waters,  when 
exposed  to  the  action  of  decaying  plants  or  animals,  out  of 
contact  of  air,  are,  like  peroxide  of  iron,  deoxidized,  and  are 
thereby  converted  into  soluble  sulphides ;  from  which,  if  car- 
bonic acid  be  present,  sulphuretted  hydrogen  gas  is  set  free. 
Such  soluble  sulphides,  or  sulphuretted  hydrogen,  are  the 
reagents  constantly  employed  in  our  laboratories  to  convert  the 
soluble  compounds  of  many  of  the  common  metals,  such  <as 
iron,  zinc,  lead,  copper,  and  silver,  into  sulphides,  which  are 
insoluble  in  water  and  in  many  acids,  and  are  thus  conven- 
iently separated  from  a  great  many  other  bodies.  Now,  when 
in  a  water  holding  iron-oxide,  sulphates  are  also  present,  the 
action  of  organic  matter,  deoxidizing  the  latter,  furnishes  the 
reagent  necessary  to  convert  the  iron  into  a  sulphide ;  which 
in  some  conditions,  not  well  understood,  contains  two  equiva- 
lents of  sulphur  for  one  of  iron,  and  constitutes  iron-pyrites. 
I  may  here  say  that  I  have  found  that  the  unstable  protosul- 
phide,  which  would  naturally  be  first  formed,  may,  under  the 
influence  of  a  persalt  of  iron,  lose  one  half  of  its  combined 
iron  •  and  that  from  this  reaction  a  stable  bisulphide  results. 
This  subject  of  the  origin  of  iron-pyrites  is  still  under  investi- 
gation. 

The  reducing  action  of  organic  matters  upon  soluble  sul- 
phates is  well  seen  in  the  sulphuretted  hydrogen  which  is 
evolved  from  the  stagnant  sea-water  in  the  hold  of  a  ship,  and 
which  coats  silver  exposed  to  it  with  a  black  film  of  sulphide 
of  silver,  and  for  the  same  reason  discolors  white-lead  paint. 
The  presence  of  sulphur  in  the  exhalations  from  some  other 
decaying  matters  is  well  known,  and  in  all  these  cases  a  solu- 
ble compound  of  iron  will  act  as  a  disinfectant,  partly  by  fixing 
the  sulphur  as  an  insoluble  sulphide.  Silver  coins  brought  from 


XII.]  ORIGIN  OF  METALLIFEROUS  DEPOSITS.  231 

the  ancient  wreck  of  a  treasure-ship  in  the  Spanish  Main  were 
found  to  be  deeply  incrusted  with  sulphide  of  silver,  formed  in 
the  ocean's  depths  by  the  process  just  explained,  which  is  one 
that  must  go  on  wherever  organic  matters  and  sea- water  are 
present,  and  atmospheric  oxygen  excluded. 

The  chemical  history  of  iron  is  peculiar ;  since  it  requires 
reducing  matters  to  bring  it  into  solution,  and  since  it  may  be 
precipitated  alike  by  oxidation,  and  by  further  reduction 
provided  sulphates  are  present.  The  metals,  copper,  lead,  and 
silver,  on  the  contrary,  form  compounds  more  or  less  soluble 
in  water,  from  which  they  are  not  precipitated  by  oxygen,  but 
only  by  reducing  agents,  which  may  separate  them  in  some 
cases  in  a  metallic  state,  but  more  frequently  as  sulphides. 
The  solubility  of  the  salts  and  oxides  of  these  metals  in  water 
is  such  that  they  are  found  in  many  mineral  springs,  in  the 
waters  that  flow  from  certain  mines,  and  in  the  ocean  itself, 
the  waters  of  which  have  been  found  to  contain  copper,  silver, 
and  lead.  Why,  then,  do  not  these  metals  accumulate  in  the 
sea,  as  the  salts  of  soda  have  done  during  long  ages  ]  The 
direct  agency  of  organic  life  comes  again  into  play,  precisely  as 
in  the  case  of  phosphorus,  iodine,  and  potash.  Marine  plants, 
which  absorb  these  from  the  sea-water,  take  up  at  the  same 
time  the  metals  just  named,  traces  of  all  of  which  are  found 
in  the  ashes  of  sea-weeds.  Copper,  moreover,  is  met  with  in 
notable  quantities  in  the  blood  of  many  marine  molluscous 
animals,  to  which  it  may  be  as  necessary  as  iron  is  to  our  own 
bodies.  Indeed,  the  blood  of  man,  and  of  the  higher  animals, 
appears  never  to  be  without  traces  of  copper  as  well  as  of 
iron. 

In  the  open  ocean  the  waters  are  constantly  aerated,  so  that 
soluble  sulphides  are  never  formed,  and  the  only  way  in  which 
these  dissolved  metals  can  be  removed  and  converted  into 
sulphides  is  by  fixing  them  in  organisms,  either  vegetable  or 
animal.  These,  by  their  decay  in  the  mud  of  the  bottom,  or 
the  lagoons  of  the  shore,  generate  the  sulphides  which  fix  their 
contained  metals  in  an  insoluble  form,  and  thus  remove  them 
from  the  terrestrial  circulation. 


232  ORIGIN  OP  METALLIFEROUS  DEPOSITS.  [XII. 

It  is  not,  however,  in  all  cases  necessary  to  invoke  the  direct 
action  of  organisms  to  separate  from  water  the  dissolved  metals. 
It  often  happens  that  the  waters  containing  these,  instead  of 
finding  their  way  to  the  ocean,  flow  into  lakes  or  enclosed 
basins,  as  in  the  case  of  the  drainage-waters  of  an  English 
copper-mine,  which  have  impregnated  the  turf  of  a  neighboring 
bog  to  such  an  extent  that  its  ashes  have  been  found  a  profita- 
ble source  of  copper.  Under  certain  conditions,  not  yet  well 
understood,  this  metal  is  precipitated  by  organic  matters  in  the 
metallic  state,  but  if  sulphates  are  present,  a  sulphide  is 
formed.  Thus,  in  certain  mesozoic  slates  in  Bohemia,  sulphide 
of  copper  is  found  incrusting  the  remains  of  fishes,  and  in  the 
sandstones  of  New  Jersey  we  find  it  penetrating  the  stems  of 
ancient  trees.  I  have  in  my  possession  a  portion  of  a  small 
trunk  taken  from  the  mud  of  a  spring  in  the  province  of 
Ontario,  in  which  the  yet  undecayed  wood  of  the  centre  is 
seen  to  be  incrusted  by  hard  and  brilliant  iron-pyrites.  In 
like  manner  the  trees  found  in  the  New  Jersey  sandstone  be- 
came incrusted  with  copper-sulphide,  which,  as  decay  went  on, 
in  great  part  replaced  the  woody  tissue.  Similar  deposits  of 
sulphides  of  copper  and  of  iron  often  took  place  in  basins 
where  the  organic  matter  was  present  in  such  a  condition  or  in 
such  quantity  as  to  be  entirely  decomposed,  and  to  leave  no 
trace  of  its  form,  unlike  the  examples  just  mentioned.  In  this 
way  have  been  formed  fahlbands,  and  beds  of  pyrites  and 
other  ores. 

The  fact  that  such  deposits  are  associated  with  silver  and 
with  gold  leads  to  the  conclusion  that  these  metals  have  obeyed 
the  same  laws  as  iron  and  copper.  It  is  known  that  both 
persalts  of  iron  and  soluble  sulphides  have  the  power  of  ren- 
dering gold  soluble,  and  its  subsequent  deposition  in  the 
metallic  state  is  then  easily  understood.* 

I  have  endeavored  by  a  few  illustrations  to  show  you  by 

what  processes  some  of  the  more  common  metals  are  dissolved 

and  again  separated  from  their  solution  in  insoluble  forms.     It 

now  remains  to  say  somewhat  of  the  geological  relations  of 

*  See  Appendix  to  this  paper. 


XII.]  ORIGIN   OF  METALLIFEROUS  DEPOSITS.  233 

ore-deposits,  which  are  naturally  divided  into  two  classes ;  the 
first  including  those  which  occur  in  beds,  and  have  been 
formed  contemporaneously  with  the  enclosing  earthy  sediments. 
Such  are  the  beds  of  iron-ores,  which  often  hold  embedded 
shells  and  other  organic  remains,  and  the  copper-bearing  strata 
already  mentioned,  in  which  the  metal  must  have  been  de- 
posited during  the  decay  of  the  animal  or  plant  which  it 
in  crusts  or  replaces.  But  there  are  other  ore-deposits  evidently 
of  more  recent  formation  than  the  rocky  strata  which  enclose 
them,  which  have  resulted  from  a  process  of  infiltration,  rilling 
up  fissures  with  the  ore,  or  diffusing  it  irregularly  through  the 
rock.  It  is  not  always  easy  to  distinguish  between  the  two 
classes  of  deposits.  Thus  a  fissure  may  in  some  cases  be  formed 
and  filled  between  two  sundered  beds,  from  which  may  result  a 
vein  that  may  be  mistaken  for  an  interposed  stratum.  Again,  a 
bed  may  be  so  porous  that  infiltrating  waters  may  diffuse  through 
it  a  metallic  ore,  or  a  metal,  in  such  a  manner  as  to  leave  it 
doubtful  whether  the  process  was  contemporaneous  with  the  de- 
position of  the  bed,  or  posterior  to  it.  But  I  wish  to  speak  of 
deposits  which  are  evidently  posterior,  and  occupy  fissures  in 
previously  formed  strata,  constituting  true  veins.  Whether 
produced  by  the  great  movements  of  the  earth's  crust,  or  by  the 
local  contraction  of  the  rocks  (and  both  of  these  causes  have  in 
different  cases  been  in  operation),  such  fissures  sometimes  extend 
to  great  lengths  and  depths;  their  arrangement  and  dimen- 
sions depending  very  much  on  the  texture  of  the  rocks  which 
have  been  subjected  to  fracture.  When  a  bone  in  our  bodies 
is  broken,  nature  goes  to  work  to  repair  the  fractured  part,  and 
gradually  brings  to  it  bony  matter,  which  fills  up  the  little 
interval,  and  at  length  makes  the  severed  parts  one  again. 
So  when  there  are  fractures  in  the  earth's  crust,  the  circulating 
waters  deposit  in  the  openings  mineral  matters,  which  unite 
the  broken  portions,  and  thus  make  whole  again  the  shattered 
rocks.  Vein-stones  are  thus  formed,  and  are  the  work  of 
nature's  conservative  surgery. 

Water,  as  we  have  seen,  is   a  universal   solvent,  and   the 
matters  which  it  may  bring  and  deposit  in  the  fissures  of  the 


234  ORIGIN   OF  METALLIFEROUS   DEPOSITS.  [XII. 

earth  are  very  various.  There  is  scarcely  a  spar  or  an  ore  to 
be  met  with  in  the  stratified  rocks  that  is  not  also  found  in 
some  of  these  vein-stones,  which  are  often  very  heterogeneous 
in  composition*  In  certain  "veins  we  find  the  elements  of  lime- 
stone or  of  granite,  and  these  often  include  the  gems,  such  as 
tourmaline,  garnet,  topaz,  hyacinth,  emerald,  and  sapphire ; 
while  others  abound  in  native  metals  or  in  metallic  oxides  or 
sulphides.  The  nature  of  the  materials  thus  deposited  depends 
very  much  on  conditions  of  temperature  and  of  pressure,  which 
affect  the  solvent  power  of  the  liquid,  and  still  more  upon  the 
nature  of  the  adjacent  rocks  and  of  the  waters  permeating 
them.  The  chemistry  of  mineral  veins  is  very  complicated. 
Many  of  these  fissures  penetrate  to  a  depth  of  thousands  of 
feet  of  the  earth's  crust,  and  along  the  channels  thus  opened 
the  ascending  heated  subterranean  waters  may  receive  in  their 
course  various  contributions  from  the  overlying  strata.  From 
these  additions,  and  from  the  diminished  solubility  resulting 
from  a  decrease  of  pressure  (ante,  page  204),  deposits  of  different 
minerals  are  formed  upon  the  walls,  and  the  slow  changes  in 
composition  are  often  represented  by  successive  layers  of  unlike 
substances.  The  power  of  these  waters  to  dissolve  and  bring 
from  the  lower  strata  their  contained  metals  and  spars  is 
probably  due  in  great  part  to  the  alkaline  carbonates  and 
sulphides  which  these  waters  often  hold  in  solution ;  but  the 
chemical  history  of  the  deposition  of  the  ores  of  iron,  lead, 
copper,  silver,  tin,  and  gold,  which  are  found  in  these  veins, 
demands  a  lengthened  study,  and  would  furnish  not  less  beau- 
tiful examples  of  nature's  chemistry  than  those  I  have  already 
laid  before  you. 

The  process  of  filling  veins  has  been  going  on  from  the  earli- 
est ages  ;  we  know  of  some  which  were  formed  before  the 
Cambrian  rocks  were  deposited,  while  others  are  still  forming, 
as  the  observations  of  Phillips  have  shown  us  in  Nevada,  whore 
hot  springs  rise  to  the  surface  and  deposit  silica,  writh  metallic 
ores,  which  incrusts  the  walls  of  the  fissures.  These  thermal 
waters  show  that  the  agencies  which  in  past  times  gave  rise  to 
the  rich  mineral  deposits  of  our  western  regions,  are  still  at 
work  there. 


XII. ]  ORIGIN   OF  METALLIFEROUS  DEPOSITS.  235 

Let  us  now  consider  the  beneficent  results  of  the  process 
of  vein-making.  The  precious  metals,  such  as  silver,  are  so 
sparsely  distributed,  that  even  the  beds  rich  in  the  products  of 
decaying  sea-weed,  which  we  have  supposed  to  be  deposited 
from  the  ocean,  would  contain  too  little  silver  to  be  profitably 
extracted.  But  in  the  course  of  ages  these  sediments,  deeply 
buried,  are  lixiviated  by  permeating  solutions,  which  dissolve 
the  silver  diffused  through  a  vast  mass  of  rock,  and  subse- 
quently deposit  it  in  some  fissure,  it  may  be  in  strata  far  above, 
as  a  rich  silver-ore.  This  is  nature's  process  of  concentration. 

We  learn  from  the  history  which  we  have  just  sketched  the 
important  conclusion,  that  amid  all  the  changes  of  the  face  of 
the  globe  the  economy  of  nature  has  remained  the  same.  "We 
are  apt,  in  explaining  the  appearances  of  the  earth's  crust,  to 
refer  the  formation  of  ore-beds  and  veins  to  some  distant  and 
remote  period,  when  conditions  very  unlike  the  present  pre- 
vailed, when  great  convulsions  took  place,  and  mysterious  forces 
were  at  work.  Yet  the  same  chemical  and  physical  laws  are 
now,  as  then,  in  operation :  in  one  part  dissolving  the  iron 
from  the  sediments  and  forming  ore-beds,  in  another  separating 
the  rarer  metals  from  the  ocean's  waters ;  while  in  still  other 
regions  the  consolidated  and  buried  sediments  are  permeated 
by  heated  waters,  to  which  they  give  up  their  metallic  matters, 
to  be  subsequently  deposited  in  veins.  These  forces  are  always 
in  operation,  rearranging  the  chaotic  admixture  of  elements 
which  results  from  the  constant  change  and  decay  around  us. 
T'he  laws  which  the  First  Great  Cause  imposed  upon  this 
material  universe  on  the  first  day  are  still  irresistibly  at  work 
fashioning  its  present  order.  One  great  design  and  purpose  is 
seen  to  bind  in  necessary  harmony  the  operations  of  the  min- 
eral with  those  of  the  vegetable  and  animal  worlds,  and  to 
make  all  of  these  contribute  to  that  terrestrial  circulation 
which  maintains  the  life  of  our  mother  earth. 

While  the  phenomena  of  the  material  world  have  been 
looked  upon  as  chemical  and  physical,  it  has  been  customary 
to  speak  of  those  of  the  organic  world  as  vital.  The  tendency 
of  modern  investigation  is,  however,  to  regard  the  processes  of 


236  ORIGIN  OF  METALLIFEROUS  DEPOSITS.  [XII. 

animal  and  vegetable  growth  as  themselves  purely  chemical 
and  physical.  That  this  is  to  a  great  extent  true  must  be 
admitted,  though  I  am  not  prepared  to  concede  that  we  have 
in  chemical  and  physical  processes  the  whole  secret  of  organic 
life.  Still  we  are,  in  many  respects,  approximating  the  phe- 
nomena of  the  organic  world  to  those  of  the  mineral  kingdom ; 
and  we  at  the  same  time  learn  that  these  so  far  interact  and 
depend  upon  each  other  that  we  begin  to  see  a  certain  truth 
underlying  the  notion  of  those  old  philosophers  who  extended 
to  the  mineral  world  the  notion  of  a  vital  force,  which  led  them 
to  speak  of  the  earth  as  a  great  living  organism,  and  to  look 
upon  the  various  changes  in  its  air,  its  waters,  and  its  rocky 
depths,  as  processes  belonging  to  the  life  of  our  planet. 


XIL]  ORIGIN  OF  METALLIFEROUS  DEPOSITS.  237 

APPENDIX. 

ON  IODINE  AND  GOLD  IN  SEA-WATER. 

AFTER  the  above  lecture  was  delivered,  appeared  the  results  of 
the  researches  of  Sonstadt  on  the  iodine  in  sea-water,  which  were 
published  in  the  Chemical  News  for  April  26,  May  17,  and  May 
24,  1872.  According  to  him,  this  element  exists  in  sea- water,  under 
ordinary  conditions,  as  iodate  of  calcium,  to  the  amount  of  about  one 
part  of  the  iodate  in  250,000  parts  of  the  water.  This  compound, 
by  decaying  organic  matter  (and  by  most  other  reducing  agents),  is 
changed  to  iodide,  from  which,  apparently  by  the  action  of  carbonic 
acid,  iodine  is  set  free,  and  may  be  separated  by  agitating  the  water 
with  bisulphide  of  carbon.  The  iodine  thus  liberated  from  sea- 
water  by  the  action  of  dead  organic  matters,  however,  slowly  de- 
composes water  in  presence  of  carbonate  of  calcium,  and  is  re- 
converted into  iodate,  the  oxygen  of  the  air  probably  intervening 
to  complete  the  oxidation,  since,  according  to  Sonstadt,  iodides  are 
readily  converted  into  iodates  under  these  conditions.  He  finds 
that  the  insolubility  of  the  iodides  of  silver  and  of  copper  is  so  great 
that  by  the  use  of  salts  of  these  metals  iodine  may  be  separated 
from  sea-water,  without  concentration,  provided  the  iodate  of  cal- 
cium has  first  been  reduced  to  iodide.  By  this  property  of  iodine 
and  its  compounds  to  oxidize  and  be  oxidized  in  turn,  Sonstadt 
supposes  them  to  perform  the  important  function  of  consuming  the 
products  of  organic  decay,  and  so  maintaining  the  salubrity  of  the 
ocean's  waters.  Their  action  would  thus  be  very  similar  to  that  of 
the  oxides  of  iron,  as  explained  in  the  lecture. 

Still  more  recently  the  same  chemist  has  announced  that  the  sea- 
water  of  the  British  coasts  contains  in  solution,  besides  silver,  an 
appreciable  amount  of  gold,  estimated  by  him  at  about  one  grain  to 
a  ton  of  water.  This  is  separated  by  the  addition  of  chloride  of 
barium  to  the  water,  apparently  as  an  aurate  of  baryta  adhering  to 
the  precipitated  sulphate,  which  yields  by  assay  an  alloy  of  about 
six  parts  of  gold  to  four  of  silver.  Other  ways  have  been  devised 
by  him  for  separating  these  metals  from  their  solution  in  sea-water. 
The  agent  which  keeps  the  gold  of  the  sea  in  a  soluble  and  oxidized 
condition  is,  according  to  Sonstadt,  the  iodine  liberated  by  the 
reaction  already  described.  The  views  maintained  by  Lieber, 


238  ORIGIN   OF  METALLIFEROUS  DEPOSITS.  [XII. 

Wurtz,  Genth,  and  Selwyn  as  to  the  solution  and  re-deposition  of 
gold  in  modern  alluvial  deposits,  seem  to  be  well-grounded,  and  we 
are  led  to  the  conclusion  that  the  circulation  of  this  metal  in  nature 
is  as  easily  effected  as  that  of  iron  or  of  copper.  The  transfer  of 
certain  other  elements,  such  as  titanium,  chrome,  and  tin,  or  at  least 
their  accumulation  in  concentrated  forms,  appears,  on  the  contrary, 
to  require  conditions  which  are  no  longer  operative,  at  least  at  the 
surface  of  the  earth. 

It  should  here  be  noticed,  that  Professor  Henry  Wurtz  of  New 
York,  in  a  paper  read  before  the  American  Association  for  the  Ad- 
vancement of  Science  in  1866,  and  published  in  the  Journal  of 
Mining  in  1868,  expressed  the  opinion  that  the  ocean- waters  con- 
tain gold,  and  urged  experiments  for  its  detection.  According  to 
his  calculations,  the  total  amount  of  gold  hitherto  extracted  from 
the  earth,  and  estimated  at  two  thousand  million  dollars,  would 
give  only  one  dollar  for  two  hundred  and  eighty  million  tons  of 
sea- water  ;  while  from  the  experiments  of  Sonstadt  it  would  appear 
that  the  same  quantity  of  gold  is  actually  contained  in  twenty-five 
tons  of  water. 


XIII. 

THE  GEOGNOSY  OF  THE  APPALACHI- 
ANS AND  THE  ORIGIN  OF  CRYSTAL- 
LINE ROCKS. 

The  following  address  was  delivered  on  retiring  from  the  office  of  president  of 
the  American  Association  for  the  Advancement  of  Science  at  Indianapolis,  August 
16,  1871.  It  appears  in  the  Proceedings  of  the  Association  and  in  the  American 
Naturalist  for  October,  and,  with  some  abridgment  of  the  first  part,  in  Nature.  A 
French  translation  of  the  entire  address  was  also  published  in  the  Revue  Scieutifique. 
In  reprinting  it  a  few  sentences  have  been  substituted  for  the  original  references 
to  the  Cambrian  rocks  of  Great  Britian,  and  a  fuller  account  of  the  Norian  or 
Labrador  series  has  been  introduced,  besides  some  minor  additions  in  the  first 
part.  In  the  second  part  of  the  paper,  also,  important  additions  have  been  made. 
These  new  portions  are  distinguished  by  being  enclosed  in  brackets. 

In  the  American  Journal  of  Science  for  February,  1872,  appeared  an  adverse  criti- 
cism of  some  parts  of  the  address,  by  Professor  J.  D.  Dana,  to  which  the  author  in  the 
same  Journal  for  July,  1872,  made  a  reply,  which  is  here  printed  as  an  appendix  to  the 
paper  ;  the  short  portion  relating  to  geognosy  being  at  the  close.  Professor  Dana's 
rejoinder  will  be  found  in  the  same  Journal  for  August,  1872. 

IN  accordance  with  our  custom  it  becomes  my  duty,  in  quit- 
ting the  honorable  position  of  president,  which  I  have  filled 
for  the  past  year,  to  address  you  upon  some  theme  which 
shall  be  germane  to  the  objects  of  the  Association.  The  pre- 
siding officer,  as  you  are  aware,  is  generally  chosen  to  represent 
alternately  one  of  the  two  great  sections  into  which  the  mem- 
bers of  the  Association  are  supposed  to  be  divided  ;  namely, 
the  students  of  the  natural-history  sciences  on  the  one  hand, 
and  of  the  physico-mathematical  and  chemical  sciences  on  the 
other.  The  arrangement  by  which,  in  our  organization,  geology 
is  classed  with  the  natural-history  division,  is  based  upon  what 
may  fairly  be  challenged  as  a  somewhat  narrow  conception  of 
its  scope  and  aims.  While  theoretical  geology  or  geogeny 
investigates  the  astronomical,  physical,  chemical,  and  biological 


240  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

laws  which  have  presided  over  the  development  of  our  earth, 
and  while  practical  geology  or  geognosy  studies  its  natural 
history  as  exhibited  in  its  physical  structure,  its  mineralogy 
and  its  paleontology,  it  will  be  seen  that  this  comprehensive 
science  is  a  stranger  to  none  of  the  studies  which  are  included 
in  the  plan  of  our  Association,  but  rather  sits  like  a  sovereign, 
commanding  in  turn  the  services  of  all. 

As  a  student  of  geology,  I  scarcely  know  with  which  section 
of  the  Association  I  should  to-day  identify  myself.  Let  me 
endeavor  rather  to  mediate  between  the  the  two,  and  show 
you  somewhat  of  the  twofold  aspect  which  geological  science 
presents,  when  viewed  respectively  from  the  standpoints  of 
natural  history  and  of  chemistry.  I  can  hardly  do  this  better 
than  in  the  discussion  of  a  subject  which  for  the  last  genera- 
tion has  afforded  some  of  the  most  fascinating  and  perplexing 
problems  for  our  geological  students ;  namely,  the  history  of 
the  great  Appalachian  mountain  chain.  Nowhere  else  in  the 
world  has  a  mountain  system  of  such  geographical  extent  and 
such  geological  complexity  been  studied  by  such  a  number  of 
zealous  and  learned  investigators,  and  no  other,  it  may  be  con- 
fidently asserted,  has  furnished  such  vast  and  important  results 
to  geological  science.  The  laws  of  mountain  structure,  as  re- 
vealed in  the  Appalachians  by  the  labors  of  the  brothers  Henry 
D.  and  William  B.  Rogers,  of  Lesley  and  of  Hall,  have  given 
to  the  world  the  basis  of  a  correct  system  of  orographic  geol- 
ogy,* and  many  of  the  obscure  geological  problems  of  Europe 
become  plain  when  read  in  the  light  of  our  American  experi- 
ence. To  discuss  even  in  the  most  summary  manner  all  of  the 
questions  which  the  theme  suggests,  would  be  a  task  too  long 
for  the  present  occasion ;  but  I  shall  endeavor  in  the  first  place 
to  bring  before  you  certain  facts  in  the  history  of  the  physical 
structure,  the  mineralogy,  and  the  paleontology  of  the  Appalachi- 
ans ;  and,  in  the  second  place,  to  discuss  some  of  the  physical, 
chemical,  and  biological  conditions  which  have  presided  over 
the  formation  of  the  ancient  crystalline  rocks  that  make  up  so 
large  a  portion  of  our  great  eastern  mountain  system. 

*  Amer.  Jour.  Sci.  (2),  XXX.  406;  and  ante,  pages  49-58. 


XIIL]  GEOGNOSY  OF  THE  APPALACHIANS.  241 


I.     THE  GEOGNOSY  OF  THE  APPALACHIAN  SYSTEM. 

The  age  and  geological  relations  of  the  crystalline  stratified 
rocks  of  eastern  .North  America  have  for  a  long  time  occupied 
the  attention  of  geologists.  A  section  across  northern  New 
York,  from  Ogdensburg  on  the  St.  Lawrence  to  Portland  in 
Maine,  shows  the  existence  of  three  distinct  regions  of  unlike 
crystalline  schists.  These  are  the  Adirondacks  to  the  west  of 
Lake  Champlain,  the  Green  Mountains  of  Vermont,  and  the 
White  Mountains  of  New  Hampshire.  The  lithological  and 
mineralogical  differences  between  the  rocks  of  these  three  re- 
gions are  sucli  as  to  have  attracted  the  attention  of  some  of  the 
earlier  observers.  Eaton,  one  of  the  founders  of  American 
geology,  at  least  as  early  as  1832  distinguished  in  his  Geologi- 
cal Text-Book  (2d  edition)  between  the  gneiss  of  the  Adiron- 
dacks and  that  of  the  Green  Mountains.  Adopting  the  then 
received  divisions  of  primary,  transition,  secondary,  and  tertiary 
rocks,  he  divided  each  of  these  series  into  three  classes,  which 
he  named  carboniferous,  quartzose,  and  calcareous  ;  meaning 
by  the  first,  schistose,  or  argillaceous  strata  such  as,  according  to 
him,  might  include  carbonaceous  matter.  These  three  divisions, 
in  fact,  corresponded  to  clay,  sand,  and  lime-rocks,  and  were 
supposed  by  him  to  be  repeated  in  the  same  order  in  each 
series.  This  was  apparently  the  first  recognition  of  that  law  of 
cycles  in  sedimentation  upon  which  I  afterwards  insisted  in 
1863.*  "Without,  so  far  as  I  am  aware,  defining  the  relations 
of  the  Adirondacks,  he  referred  to  the  lowest  or  carboniferous 
division  of  the  primary  series,  the  crystalline  schists  of  the 
Green  Mountains,  while  the  quartzites  and  marbles  at  their 
western  base  were  made  the  quartzose  and  calcareous  divisions 
of  this  primary  series.  The  argillites  and  sandstones  lying  still 
farther  westward,  but  to  the  east  of  the  Hudson  River,  were 
regarded  as  the  first  and  second  divisions  of  the  transition  se- 

*  Amer.  Jour.  Sci.  (2),  XXXV.  166.  See,  for  an  excellent  presentation  of 
this  subject,  with  references  to  its  literature,  a  paper  by  Dr.  Newberry  in  the 
Proceedings  of  the  American  Association  for  the  Advancement  of  Science  for 
1873,  page  185. 

11"  P 


242  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

ries,  and  were  followed  by  its  calcareous  division,  which  seems 
to  have  included  the  limestones  of  the  Trenton  group ;  all  of 
these  rocks  being  supposed  to  dip  to  the  westward,  and  away 
from  the  central  axis  of  the  Green  Mountains.  Eaton  does  not 
appear  to  have  studied  the  White  Mountains,  nor  to  have  con- 
sidered their  geological  relations.  They  were,  however,  clearly 
distinguished  from  the  former  by  Charles  T.  Jackson  in  1844, 
when,  in  his  report  on  the  geology  of  New  Hampshire,  he  de- 
scribed the  White  Mountains  as  an  axis  of  primary  granite, 
gneiss,  and  mica-schist,  overlaid  successively,  both  to  the  east 
and  west,  by  what  were  designated  by  him  Cambrian  and  Silu- 
rian rocks ;  these  names  having,  since  the  time  of  Eaton's  pub- 
lication, been  introduced  by  English  geologists.  While  these 
overlying  rocks  in  Maine  were  unaltered,  he  conceived  that  the 
corresponding  strata  in  Vermont,  on  the  western,  side  of  the 
granitic  axis,  had  been  changed  by  the  action  of  intrusive  ser- 
pentines and  intrusive  quartzites,  which  had  altered  the  Cam- 
brian into  the  Green  Mountain  gneiss,  and  converted  a  portion 
of  the  fossiliferous  Silurian  limestones  of  the  Champlain  valley 
into  white  marbles.*  Jackson  did  not  institute  any  compari- 
son between  the  rocks  of  the  White  Mountains  and  those  of 
the  Adirondacks ;  but  the  Messrs.  Rogers  in  the  same  year, 
1844,  published  an  essay  on  the  geological  age  of  the  White 
Mountains,  in  which,  while  endeavoring  to  show  their  Silurian 
age,  they  speak  of  them  as  having  been  hitherto  regarded  as 
consisting  exclusively  of  various  modifications  of  granitic  and 
gneissoid  rocks,  and  as  belonging  "to  the  so-called  primary 
periods  of  geologic  time."  t  They,  however,  considered  that 
these  rocks  had  rather  the  aspect  of  altered  palaeozoic  strata,  and 
suggested  that  they  might  be,  in  part,  at  least,  of  the  age  of  the 
Clinton  division  of  the  New  York  system ;  a  view  which  was 
supported  by  the  presence  of  what  were  at  the  time  regarded 
by  the  Messrs.  Eogers  as  organic  remains.  Subsequently,  in 
1847,J  they  announced  that  they  no  longer  considered  these  to 

*  Geology  of  New  Hampshire,  160-162. 
t  Amer.  Jour.  Sci.  (2),  I.  411. 
i  Ibid.  (2),  V.  116. 


XIIL]  GEOGNOSY  OF  THE  APPALACHIANS.  243 

be  of  organic  origin,  without,  however,  retracting  their  opinion 
as  to  the  palaeozoic  age  of  the  strata.  Reserving  to  another 
place  iii  my  address  the  discussion  of  the  geological  age  of  the 
White  Mountain  rocks,  I  proceed  to  notice  briefly  the  distinc- 
tive characters  of  the  three  groups  of  crystalline  strata  just 
mentioned,  which  will  be  shown  in  the  sequel  to  have  an  im- 
portance in  geology  beyond  the  limits  of  the  Appalachians. 

I.  Tlie  Adirondack  or  Laurentide  Series.  —  The  rocks  of  this 
series,  to  which  the  name  of  the  Laurentian  system  has  been 
given,  may  be  described  as  chiefly  firm  granitic  gneisses,  often 
very  coarse  grained,  and  generally  reddish  or  grayish  in  color. 
They  are  frequently  hornblendic,  but  seldom   or   never   con- 
tain much  mica,  and  the  mica-schists  (often  accompanied  with 
staurolite,  garnet,  andalusite,  and  cyanite),  so  characteristic  of 
the  White  Mountain  series,  are  wanting  among  the  Laurentian 
rocks.     They  are  also  destitute  of  argillites,  which  are  found  in 
the  other  two  series.     The  quartzites,  and  the  pyroxenic  and 
hornblendic  rocks,  associated  with  great  formations  of  crystal- 
line limestone,  with  graphite,  and  immense  beds  of  magnetic 
iron-ore,  give  a  peculiar  character  to  portions  of  the  Laurentian 
system. 

II.  TJie  Green  Mountain  Series. — The  qrfartzo-feldspathic 
rocks  of  this  series  are  to  a  considerable  extent  represented  by 
a  fine-grained  petrosilex  or  eurite,  though  they  often   assume 
the  form  of  a  true  gneiss,  which  is  ordinarily  more  micaceous 
than  the  typical  Laurentian  gneiss.     The  coarse -grained,  por- 
phyritic,  reddish  varieties  common  to  the  latter  are  wanting  in 
the  Green  Mountains,  where  the  gneiss  is  generally  of  pale 
greenish   and   grayish   hues.     [The   quartziferous    porphyries, 
which  have  been  noticed  ante,  page  187,  are  supposed,  in  the 
present  state  of  our  knowledge,  to  belong  to  this  series.]     Mas- 
sive stratified  diorites,  and  epidotic  and  chloritic  rocks,  often 
more  or  less  schistose,  with  steatites,  dark-colored  serpentines, 
and  ferriferous  dolomites  and  magnesites  also  characterize  this 
gneissic  series,  and  are  intimately  associated  with  beds  of  iron- 
ore,  generally  a   slaty   hematite,    but   occasionally   magnetite. 
Chrome,  titanium,  nickel,  copper,  antimony,  and  gold  are  fre- 


244  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

quently  met  with  in  this  series.  The  gneisses  often  pass  into 
schistose  micaceous  quartzites,  and  the  argillites,  which  abound, 
frequently  assume  a  soft  unctuous  character,  which  has  acquired 
for  them  the  name  of  talcose  or  nacreous  slates,  though  analysis 
shows  them  not  to  be  magnesian,  but  to  consist  essentially  of 
a  hydrous  micaceous  mineral  allied  to  paragonite.  They  are 
sometimes  black  and  graphitic. 

III.  The  White  Mountain  Series.  —  This  series  is  character- 
ized by  the  predominance  of  well-defined  mica-schists  interstrati- 
fied  with  micaceous  gneisses.  These  latter  are  ordinarily  light 
colored  from  the  presence  of  white  feldspar,  and,  though  gener- 
ally fine  in  texture,  are  sometimes  coarse  grained  and  porphy-- 
ritic.  They  are  less  strong  and  coherent  than  the  gneisses  of 
the  Laurentian,  and  pass,  through  the  predominance  of  mica, 
into  mica-schists,  which  are  themselves  more  or  less  tender  and 
friable,  and  present  every  variety,  from  a  coarse  gneiss-like 
aggregate  down  to  a  fine-grained  schist,  which  passes  into  ar- 
gillite.  The  micaceous  schists  of  this  series  are  generally  much 
richer  in  mica  than  those  of  the  preceding  series,  and  often 
contain  a  large  proportion  of  well-defined  crystalline  tables 
belonging  to  the  species  muscovite.  The  cleavage  of  these 
micaceous  schists  is  generally,  if  not  always,  coincident  with 
the  bedding ;  but  the  plates  of  mica  in  the  coarser-grained 
varieties  are  often  arranged  at  various  angles  to  the  cleavage 
and  bedding-plane,  showing  that  they  were  developed  after 
sedimentation,  by  crystallization  in  the  mass,  a  circumstance 
which  distinguishes  them  from  rocks  derived  from  the  ruins  of 
these,  which  are  met  with  in  more  recent  series.  The  White 
Mountain  rocks  also  include  beds  of  micaceous  quartzite.  The 
basic  silicates  in  this  series  are  represented  chiefly  by  dark- 
colored  gneisses  and  schists  in  which  hornblende  takes  the 
place  of  mica.  These  pass  occasionally  into  beds  of  dark  horn- 
blende rock,  sometimes  holding  garnets.  Beds  of  crystalline 
limestone  occur  in  the  schists  of  the  White  Mountain  series, 
and  are  sometimes  accompanied  by  pyroxene,  garnet,  idocrase, 
sphene,  and  graphite,  as  in  the  corresponding  rocks  of  the 
Laurentian,  which  this  series,  in  its  more  gneissic  portions, 


XIII.]  GEOGNOSY  OF  THE  APPALACHIANS.  245 

closely  resembles,  though  apparently  distinct  geognostically. 
The  limestones  are  intimately  associated  with  the  highly  mi- 
caceous schists  containing  staurolite,  andalusite,  cyanite,  and 
garnet.  These  schists  are  sometimes  highly  plumbaginous,  as 
seen  in  the  graphitic  mica-schist  holding  garnets  in  Nelson, 
New  Hampshire,  and  that  associated  with  cyanite  in  Cornwall, 
Connecticut.  To  this  third  series  of  crystalline  schists  belong 
the  concretionary  granitic  veins  abounding  in  beryl,  tourma- 
line, and  lepidolite,  and  occasionally  containing  tinstone  and 
columbite.  (See  Granites  and  Granitic  Vein-Stones,  ante,  pages 
194-199.)  Granitic  veins  in  the  Laurentian  gneisses  fre- 
'quently  contain  tourmaline,  but  have  not,  so  far  as  yet  known, 
yielded  the  other  mineral  species  just  mentioned. 

Keeping  in  mind  the  characteristics  of  these  three  series,  it 
will  be  easy  to  trace  them  southward  by  the  aid  of  the  concise 
and  accurate  descriptions  which  Professor  H.  D.  Rogers  has 
given  us  of  the  rocks  of  Pennsylvania.  In  his  report  on  the 
geology  of  this  State,  he  has  distinguished  three  districts  of 
various  crystalline  schists,  which  are  by  him  included  together 
under  the  name  of  gneissic  or  hypozoic  rocks.  Of  these  dis- 
tricts, the  most  northern,  or  the  South  Mountain  belt,  to  the 
northwest  of  the  Mesozoic  basin,  is  said  to  be  the  continuation 
of  the  Highlands  of  New  York  and  New  Jersey,  which,  cross- 
ing the  Delaware  near  Easton,  is  continued  southward,  through 
Pennsylvania  and  Maryland,  into  Virginia,  where  it  appears  in 
the  Blue  Ridge.  The  gneiss  of  this  district  in  Pennsylvania 
is  described  as  differing  considerably  from  that  of  the  southern- 
most district,  being  massive  and  granitoid,  often  hornblendic, 
with  much  magnetic  iron,  but  destitute  of  any  considerable 
beds  of  micaceous,  talcose,  or  chloritic  slate,  which  mark  the 
rocks  of  the  southern  district.  These  characters  are  sufficient 
to  show  that  the  gneiss  of  this  northern  district  is  lithologi- 
cally,  as  well  as  geognostically,  identical  with  that  of  the 
Highlands,  and  belongs,  like  it,  to  the  Adirondack,  or  Lauren- 
tian system  of  crystalline  rocks.  The  gneiss  of  the  middle 
district  of  Pennsylvania,  to  the  south  of  the  Mesozoic,  but 
north  of  the  Chester  valley,  is  described  by  Rogers  as  resein- 


246  GEOGNOSY   OF  THE  APPALACHIANS.  [XIII. 

"bling  that  of  the  South  Mountain,  or  northern  district,  and  to 
consist  chiefly  of  white  feldspathic  and  dark  hornblendic  gneiss, 
with  very  little  mica,  and  with  crystalline  limestones. 

The  gneiss  of  the  third  or  southern  district  (that  lying  to 
the  south  of  the  Montgomery  and  Chester  valleys)  comes  from 
beneath  the  Mesozoic  of  New  Jersey  about  six  miles  north- 
east of  Trenton,  and,  stretching  southwest  ward,  occupies  the 
southern  border  of  Pennsylvania,  extending  into  Delaware  and 
Maryland.  It  is  subdivided  by  Rogers  into  three  belts.  The 
first  or  most  southern  of  these,  passing  through  Philadelphia, 
consists  of  alternations  of  dark  hornblendic  and  highly  mica- 
ceous gneiss,  with  abundance  of  mica-slate,  sometimes  coarse 
grained,  and  at  other  times  so  fine  grained  as  to  constitute  a 
sort  of  whet-slate.  To  the  northwestward  the  strata  become 
still  more  micaceous,  with  garnets  and  beds  of  hornblende 
slate,  till  we  reach  the  second  subdivision,  which  consists  of  a 
great  belt  of  highly  talcose  and  micaceous  schists,  with  steatite 
and  serpentine,  and  is  in  its  turn  succeeded  by  a  third  narrow 
belt,  resembling  the  less  micaceous  members  of  the  first  or 
southernmost  subdivision.  The  micaceous  schists  of  this  re- 
gion abound  in  staurolite,  garnet,  cyanite,  and  corundum,  and 
are  traversed  by  numerous  irregular  granitic  veins  containing 
beryl  and  tourmaline.  All  of  these  characters  lead  us  to  refer 
the  gneiss  of  this  southern  district  to  the  third,  or  White 
Mountain  series,  with  the  exception  of  the  middle  subdivision, 
which  presents  the  aspect  of  the  second,  or  Green  Mountain 
series. 

Above  the  hypozoic  gneisses  Rogers  has  placed  his  azoic  or 
semi-rnetamorphic  series,  which  is  traceable  from  the  vicinity 
of  Trenton  to  the  Schuylkill,  along  the  northern  boundary  of 
the  southern  hypozoic  gneiss  district.  This  series  is  supposed 
by  Rogers  to  be  an  altered  form  of  the  primal  sandstones  and 
slates,  and  is  described  as  consisting  of  a  feldspathic  quartzite, 
or  eurite,  containing  in  some  cases  porphyritic  beds  with  crys- 
tals of  feldspar  and  hornblende,  together  with  various  crystal- 
line schists  ;  including,  in  fact,  the  whole  of  the  great  serpentine 
belt  of  Montgomery,  Chester,  and  Lancaster  Counties,  with  its 


XIII.]  GEOGNOSY  OF  THE  APPALACHIANS.  247 

steatites,  hornblendic,  dioritic,  chloritic,  and  micaceous  schists 
(often  garnet-bearing),  together  with  a  band  of  argillite,  afford- 
ing roofing-slates.  With  this  great  series  are  associated  chromic 
and  titanic  iron,  and  ores  of  nickel  and  copper.  Veins  of 
albite  with  corundum  also  intersect  this  series  near  Uniouville. 
We  are  repeatedly  assured  by  Rogers  that  these  rocks  so  much 
resemble  the  underlying  hypozoic  gneiss,  as  to  be  readily  con- 
founded with  them;  and  when  compared  with  the  latter,  as 
displayed  in  the  southern  district,  it  is  difficult  to  believe  that 
we  have  in  this  so-called  azoic  or  metamorphic  series  of  the 
Montgomery  and  Chester  valleys  anything  else  than  a  repeti- 
tion of  these  same  crystalline  schists  which  have  been  described 
along  their  southern  boundary,  representing  the  Green  Moun- 
tain and  the  White  Mountain  series.  We  thus  avoid  the 
difficulty  of  supposing  that  we  have  in  this  region  two  sets  of 
serpentine  rocks,  and  two  of  mica-schists,  lithologically  similar, 
but  of  widely  different  ages,  —  a  conclusion  highly  improbable. 
It  should  be  said  that  Rogers,  in  accordance  with  the  notions 
then  generally  received,  looked  upon  serpentine  as  an  eruptive 
rock,  which  had  altered  the  adjacent  strata,  converting  the 
mica-schists  into  steatitic  and  chloritic  rocks. 

This  so-called  azoic  series,  according  to  Rogers,  underlies  the 
auroral  limestone  of  Pennsylvania,  thus  apparently  occupying 
the  horizon  of  the  primal  palaeozoic  division.  We  find,  how- 
ever, in  his  report  on  the  geology  of  the  State,  no  satisfactory 
evidence  of  the  identity  of  the  two  series  of  crystalline  rocks. 
On  the  contrary,  a  very  different  conclusion  would  seem  to 
follow  from  certain  facts  there  detailed.  The  azoic  or  so-called 
metamorphic  primal  strata  are  said  to  have  a  very  uniform 
nearly  vertical  dip,  or  with  high  angles  to  the  southward,  while 
the  micaceous  and  gneissic  strata  of  the  northern  subdivision 
of  the  southern  district  of  so-called  hypozoic  rocks,  limiting 
these  last  to  the  south,  present  either  minute  local  contortions 
or  wide  gentle  undulations,  with  comparatively  moderate  dips, 
for  the  most  part  to  the  northward.*  From  this,  I  think, 
we  may  infer  that  the  nearly  vertical  strata  must  be,  in  truth, 
*  Rogers,  Geology  of  Pennsylvania,  I.  pp.  69-74,  and  154-158. 


248  GEOGNOSY   OF  THE  APPALACHIANS.  [XIII. 

older  underlying  rocks  belonging,  not  to  the  palaeozoic  system, 
but  to  our  second  series  of  crystalline  schists.  We  conclude, 
then,  that  while  the  gneisses  to  the  northwest,  and  probably 
those  along  the  southeast  rim  of  the  mesozoic  basin  of  Penn- 
sylvania, are  Laurentian,  the  great  valley  southward  to  the 
Delaware  is  occupied  by  the  rocks  of  the  Green  Mountain 
and  White  Mountain  series.  The  same  two  types  of  rocks, 
extending  to  the  northeast,  are  developed  about  New  York 
City,  in  the  mica-schists  of  Manhattan  and  the  serpentines  of 
Staten  Island  and  Hoboken ;  while  in  the  range  of  the  High- 
lands, the  Laurentian  gneiss  belt  of  the  South  Mountain 
crosses  the  Hudson  Eiver. 

The  three  series  of  gneissic  rocks  which  we  have  distin- 
guished in  our  section  to  the  northward  have,  in  southeastern 
New  York,  as  in  Pennsylvania,  been  grouped  together  in  the 
primary  system,  and  may  thence  all  be  traced  into  western 
New  England.  In  Dr.  Percival's  Geological  Report  and  Map 
of  Connecticut,  published  in  1840,  it  will  be  seen  that  he 
refers  to  the  gneiss  of  the  Highlands  two  gneissic  areas  in 
Litchfield  County ;  the  one  occupying  parts  of  Cornwall  and 
Ellsworth,  and  the  other  extending  from  Torrington,  north- 
ward through  Winchester,  Norfolk,  and  Colebrooke  into  Berk- 
shire County,  Massachusetts.  Further  investigations  may 
confirm  the  accuracy  of  Percival's  identification,  and  show  the 
Laurentian  age  of  these  New  England  gneisses,  a  view  which 
is  apparently  supported  by  the  mineralogical  characters  of 
some  of  the  rocks  in  this  region.  Emmons  informs  us  that 
primary  limestones  with  graphite  (perhaps  Laurentian)  are 
met  with  in  the  Hoosic  range  in  Massachusetts  east  of  the 
Stockbridge  (Taconic)  limestones. 

The  rocks  of  the  second  series  are  traceable  from  south- 
western Connecticut  northward  to  the  Green  Mountains  in 
Vermont,  and  the  micaceous  schists  and  gneisses  of  the  third, 
or  White  Mountain  series  are  found  both  to  the  east  and  the 
west  of  the  mesozoic  valley  in  Connecticut  and  Massachusetts. 
They  also  occupy  a  considerable  area  in  eastern  Vermont, 
where  they  are  separated  from  the  White  Mountain  range  by 


XIII.]  GEOGNOSY  OF  THE  APPALACHIANS.  249 

an  outcrop  of  rocks  of  the  second  series.  To  the  southeast  of 
the  White  Mountains,  along  our  line  of  section,  the  same 
mica-schists  and  gneisses,  often  with  very  moderate  dips,  ex- 
tend as  far  as  Portland,  Maine,  where  they  are  interrupted  by 
the  outcropping  of  greenish  chloritic  and  chromiferous  schists, 
in  nearly  vertical  beds,  which  appear  to  belong  to  the  second 
series. 

I  find  that  the  strata  of  the  second  series  appear  from  be- 
neath the  Carboniferous  at  Newport,  Rhode  Island,  in  a  nearly 
vertical  attitude,  and  are  also  seen  in  the  vicinity  of  Boston 
and  Brighton,  Saugus  and  Lynnfield.  Their  relations  in  this 
region  to  the  gneisses  with  crystalline  limestones  of  Chelms- 
ford,  etc.,  which  I  have  referred  to  the  Laurentian  series,* 
have  yet  to  be  determined. 

We  have  already  mentioned  that  the  crystalline  rocks  of 
Pennsylvania  pass  into  Maryland  and  Virginia,  where,  as  H.  D. 
Rogers  informs  us,  they  appear  in  the  mountains  of  the  Blue 
Ridge.  It  remains  to  be  seen  whether  the  three  types  which 
we  have  pointed  out  in  Pennsylvania  are  to  be  recognized  in 
this  region.  A  great  belt  of  crystalline  schists  extends  from 
Virginia  through  North  and  South  Carolina,  and  into  eastern 
Tennessee,  where,  according  to  Safford,  these  rocks  underlie 
the  Potsdam.  It  is  easy,  from  the  reports  of  Lieber  on  the 
geology  of  South  Carolina,  to  recognize  in  this  State  the  two 
types  of  the  Green  Mountain  and  White  Mountain  series. 
The  former,  as  described  by  him,  consists  of  talcose,  chloritic, 
and  epidotic  schists,  with  diorites,  steatites,  actinolite-rock,  and 
serpentines.  It  may  be  noted  that  he  still  adheres  to  the 
notion  of  the  eruptive  origin  of  the  last  three  rocks,  which  the 
observations  of  Emmons,  Logan,  and  myself  in  the  Green 
Mountains  have  shown  to  be  untenable.  These  rocks  in  South 
Carolina  generally  dip  at  very  high  angles.  The  great  gneissic 
area  of  Anderson  and  Abbeville  districts  is  described  by  Lieber 
as  consisting  of  fine-grained  gray  gneisses  with  •  micaceous  and 
hornblendic  schists,  and  is  cut  by  numerous  veins  of  pegmatite, 
holding  garnet,  tourmaline,  and  beryl.  These  rocks,  which 

*  American  Journal  of  Science  (2),  XLIX.  75. 
11* 


250  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

have  the  characters  of  the  White  Mountain  series,  appear,  from 
the  incidental  observations  to  be  found  in  Lieber's  reports,  to 
belong  to  a  higher  group  than  the  chloritic  and  serpentine 
series,  and  to  dip  at  comparatively  moderate  angles.* 

Professor  Emmons,  whose  attention  was  early  turned  to  the 
geology  of  western  New  England,  did  not  distinguish  between 
the  three  types  which  we  have  denned,  but,  like  Rogers  in 
Pennsylvania,  included  all  the  crystalline  rocks  of  that  region 
in  the  primary  system.  It  is  to  him,  however,  that  we  owe 
the  first  correct  notions  of  the  geological  nature  and'  relations 
of  the  Green  Mountains.  These,  he  has  remarked,  are  often 
made  to  include  two  ranges  of  hills  belonging  to  different 
geological  series.  The  eastern  range,  including  the  Hoosic 
Mountain  in  Massachusetts  and  Mount  Mansfield  in  Vermont, 
he  referred  to  the  primary ;  which  he  described  as  including 
gneiss,  mica-schist,  talcose  slate,  and  hornblende,  with  beds  and 
veins  of  granite,  limestone,  serpentine,  and  trap.  He  declared, 
moreover,  that  there  is  no  clear  line  of  demarcation  among  the 
various  schistose  primary  rocks,  and  cited,  as  an  illustration, 
the  passage  into  each  other  of  serpentine,  steatite,  and  talcose 
schist.  His  description  of  the  crystalline  rocks  of  this  range 
will  be  recognized  as  comprehensive  and  truthful. 

[*  My  own  observations  have  since  shown  me  that  the  rocks  of  the  White 
Mountain  series  are  largely  displayed,  and  rarely  at  high  angles,  in  the  Blue 
Eidge  in  CaiToll  County,  Virginia,  thence  southwestward  at  least  as  far  as 
Ashe  County,  North  Carolina,  and  again  in  Polk  County,  Tennessee.  The 
lithological  study  in  these  regions  is  rendered  difficult  by  the  fact  that  they 
are  covered,  often  to  a  depth  of  a  hundred  feet  or  more,  by  the  undisturbed 
products  of  their  own  decomposition,  the  protoxide  bases  having  been  re- 
moved by  solution  from  the  feldspar  and  the  hornblende,  and  the  whole  rock, 
with  the  exception  of  the  quartzose  layers,  reduced  to  a  clayey  mass,  still, 
however,  showing  the  inclined  planes  of  stratification.  The  immense  veins 
of  pyritous  copper-ores,  which  these  rocks  enclose  (ante,  page  217),  have  in 
like  manner  been  changed,  to  as  great  depths,  into  hydrous  peroxide  of  iron. 
I  have  already  alluded  to  the  significance,  both  chemical  and  geological,  of 
this  decomposition,  and  to  its  great  antiquity  (ante,  page  10).  The  observa- 
tions of  C.  A.  White,  in  the  northwest,  show  that  such  a  decomposition  of 
the  Eozoic  gneisses  was  antei'ior  to  the  cretaceous  period,  while  in  Missouri, 
it  appears  from  the  studies  of  R.  Pumpelly,  confirmed  by  my  own  observa- 
tions, that  the  quartziferous  porphyries  with  which  the  iron-ores  of  that 
region  occur,  were  thus  decomposed  before  the  deposition  of  the  Cambrian 
sandstones.] 


XIIL]  GEOGNOSY  OF  THE  APPALACHIANS.  251 

To  the  west  of  the  hills  of  primary  schist,  he  placed  his 
Taconic  system,  named  from  the  Taconic  hills,  which  run  from, 
north  to  south  along  the  boundary  line  of  New  York  and 
Massachusetts,  and  form  a  range  parallel  with  the  Green  Moun- 
tains. The  lower  portions  of  the  Taconic  system,  according  to 
Emmons,  are  schistose  rocks  made  up  from  the  ruins  of  the 
primary  schists  which  lie  to  the  east  of  them.  Thus  the  talcose 
schists  of  Berkshire  are  said  to  be  regenerated  rocks,  belonging 
to  the  newer  system,  but  showing  the  color  and  texture  of  the 
older  talcose  schists  from  which  they  were  formed.  How  far 
this  is  true  of  these  particular  strata  may  be  a  question,  for 
there  is  reason  to  believe  that  Emmons  included  among  his 
Taconic  rocks  some  beds  belonging  to  the  older  crystalline 
series  of  the  Green  Mountains ;  yet  it  is  not  less  true  that  the 
possibility  of  derived  rocks  of  this  kind  is  one  which  has  been 
too  much  overlooked  by  geologists.*  Emmons  elsewhere  re- 
marks that,  while  the  talcose  slates  of  the  primary  are  associated 
with  steatite  and  with  hornblende,  these  are  never  found  in 
the  Taconic  rocks,  and  also,  that  epidote,  actinolite,  titanium, 
(rutile),  etc.,  which  are  characteristic  minerals  of  the  primary, 
are  wanting  in  the  Taconic  system. 

The  statements  of  Emmons  on  this  point  were  sufficiently 
explicit ;  he  included  in  the  primary  system  all  of  the  crystal- 
line schists  of  the  Green  .Mountains,  except  certain  talcose  and 
micaceous  beds,  which  he  supposed  to  be  made  up  of  the  ruins 
of  the  similar  strata  in  the  primary,  and  to  constitute,  with  a 
great  mass  of  other  rocks,  the  Taconic  system ;  which  was,  in 
its  turn,  unconfonnably  overlaid  by  the  Potsdam  sandstone 
and  Calciferous  sand-rock  of  the  New  York  system.  His  views 
have,  however,  been  misunderstood  by  more  than  one  of  his 
critics  ;  thus,  Mr.  Marcou,  while  defending  the  Taconic  system, 
makes  it  to  include  the  three  groups  just  mentioned,  namely, 
1.  The  Green  Mountain  gneiss ;  2.  The  Taconic  strata  as 
defined  by  Emmons  ;  and,  3.  The  Potsdam  sandstone ;  t  thus 

*  Some  observations  on  this  point  will  be  found  in  Essay  XIV. 
t  Proceedings  of  Boston  Society  of  Natural  History,  November  6, 1861,  and 
American  Journal  of  Science  (2),  XXXIII.  282. 


252  GEOGNOSY   OF  THE  APPALACHIANS.  [XIII. 

uniting  in  one  system  the  crystalline  schists  and  the  overlying 
uncrystalline  fossiliferous  sediments,  in  direct  opposition  to  the 
plainly  expressed  teachings  of  Emmons,  as  laid  down  in  his 
report  on  the  geology  of  the  Northern  District  of  New  York, 
and  later,  in  1846,*  in  his  memoir  on  the  Taconic  System. 

In  the  geological  survey  of  the  State  of  New  York,  the 
rocks  of  the  Champlain  division  (including  the  strata  from  the 
base  of  the  Potsdam  sandstone  to  the  summit  of  the  Loraine 
or  Hudson  River  shales)  had,-  by  his  colleagues,  been  looked 
upon  as  the  lowest  of  the  palaeozoic  system.  Professor  Em- 
mons, however,  was  led  to  regard  the  very  dissimilar  strata  of 
the  Taconic  hills  as  constituting  a  distinct  and  more  ancient 
series.  A  similar  view  had  been  held  by  Eaton,  who  placed, 
as  we  have  already  seen,  above  the  crystalline  schists  of  the 
Green  Mountains,  his  primary  quartzose  and  calcareous  forma- 
tions, followed  to  the  westward  by  transition  argillites  and 
sandstones,  which  latter  appear  to  have  corresponded  to  the 
Potsdam  sandstone  of  New  York.  Emmons,  however,  gave  a 
greater  form  and  consistency  to  this  view,  and  endeavored  to 
sustain  it  by  the  evidence  of  fossils,  as  well  as  by  structure. 
The  Taconic  system,  as  denned  by  him,  may  be  briefly  de- 
scribed as  a  series  of  uncrystalline  fossiliferous  sediments 
reposing  unconformably  on  the  crystalline  schists  of  the  Green 
Mountains,  and  partly  made  up  of  their  ruins  ;  while  it  is,  at 
the  same  time,  overlaid  unconformably  by  the  Potsdam  and 
Calciferous  formations  of  the  Champlain  division,  and  consti- 
tutes the  true  base  of  the  pala3ozoic  column. 

Although  he  claimed  to  have  traced  this  Taconic  system 
throughout  the  Appalachian  chain  from  Maine  to  North  Caro- 
lina, it  is  along  the  confines  of  Massachusetts  and  New  York 
that  its  development  was  most  minutely  studied.  He  separated 
it  into  a  lower  and  an  upper  division,  and  estimated  its  total 
thickness  at  not  less  than  thirty  thousand  feet,  consisting,  in 
the  order  of  deposition,  of  the  following  members  :  1.  Granu- 

*  Loc.  cit.  p.  130,  and  Agriculture  of  New  York,  I.  53.  This  formed  a 
part  of  the  report  by  Emmons  on  the  Agriculture  of  New  York,  but  was 
also  published  separately. 


XIIL]  GEOGNOSY  OF  THE  APPALACHIANS.  253 

lar  quartz ;  2.  Stockbridge  limestone ;  3.  Magnesian  slate ; 
4.  Sparry  limestone ;  5.  Roofing-slate,  graptolitic ;  6.  Sili- 
cious  conglomerate ;  7.  Taconic  slate ;  8.  Black  slate.  The 
apparent  order  of  superposition  differs  from  this,  and  it  was 
conceived  by  Professor  Emmons  that  during  the  accumulation 
of  these  Taconic  rocks,  the  Green  Mountain  gneiss,  which 
formed  the  eastern  border  of  the  basin,  was  gradually  elevated 
so  as  to  bring  successively  the  older  members  above  the  ocean 
from  which  the  sediments  were  being  deposited.  From  this  it 
resulted  that  the  upper  members  of  the  system,  such  as  the 
black  slates,  were  confined  to  a  very  narrow  belt,  and  never 
extended  far  eastward ;  although  he  admits  that  denudation 
may  have  removed  large  portions  of  these  upper  beds.  At  a 
subsequent  period,  a  series  of  parallel  faults,  with  upthrows  on 
the  eastern  side,  is  supposed  to  have  broken  the  strata,  given 
them  an  eastward  dip,  and  caused  the  newer  beds  to  pass  suc- 
cessively beneath  the  older  ones,  thus  producing  an  apparently 
inverted  succession,  and  making  their  present  seeming  order  of 
superposition  completely  deceptive.  In  speaking  of  this  sup- 
posed arrangement  of  the  members  of  his  Taconic  system, 
Emmons  alluded  to  them  as  "  inverted  strata  " ;  while  by  Mr. 
Marcou,  the  strata  were  said  to  be  "  overturned  on  each  side 
of  the  crystalline  and  eruptive  rocks  which  occupy  the  centre 
of  the  chain,  producing  thus  a  fan-shaped  structure,"  etc.*  I 
have  elsewhere  shown  that  this  notion,  though  to  some  extent 
countenanced  by  his  vague  and  inaccurate  use, of  terms,  was 
never  entertained  by  Emmons,  whose  own  view,  as  defined  in 
his  Taconic  System  (p.  17),t  is  that  just  explained. 


»  Comptes  Rendus  de  1'Academie,  LIII.  804. 

+  See  my  further  discussion  of  the  matter,  American  Journal  of  Science 
(2),  XXXII.  427 ;  XXXIII.  135,  281.  It  is  by  an  oversight  that  I  have,  in 
the  latter  volume  (page  136),  represented  Barrande  as  sharing  the  miscon- 
ception of  Marcou,  although  his  language,  without  careful  scrutiny,  would 
lead  us  to  such  a  conclusion.  In  fact,  in  the  Bull.  Soc.  Geol.  de  France 
((2),  XVIII.  261),  in  an  elaborate  study  of  the  Taconic  question,  Barrande 
heads  a  section  thus  :  "  Renversement  conpu  pour  tmit  un  fysfeme,"  and  then 
proceeds  to  show  that  the  renversement  or  overturn  is  only  apparent,  by 
explaining,  in  the  language  of  Emmons,  the  view  already  set  forth  above. 


254  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

The  view  of  Emmons,  that  there  exists  at  the  western  base 
of  the  Green  Mountains  an  older  fossiliferous  series,  underlying 
the  Potsdam,  met  with  general  opposition  from  American  ge- 
ologists. In  May,  1844,  H.  D.  Rogers,  in  his  address  as  presi- 
dent, before  the  American  Association  of  Geologists,  then  met 
at  Washington,  criticised  this  view  at  length,  and  referred  to  a 
section  from  Stockbridge,  Massachusetts,  to  the  Hudson  River, 
made  by  W.  B.  Rogers  and  himself,  and  by  them  laid  before 
the  American  Philosophical  Society  in  January,  1841.  They 
then  maintained  that  the  quartz-rock  of  the  Hoosic  range  was 
Potsdam,  the  Berkshire  marble  identical  with  the  blue  lime- 
stone of  the  Hudson  valley,  and  the  associated  micaceous  and 
talcose  schists  altered  strata  of  the  age  of  the  slates  at  the 
base  of  the  Appalachian  system  ;  that  is  to  say,  primal  in  the 
nomenclature  of  the  Pennsylvania  survey. 

In  1843  Mather  had  asserted  the  Champlain  age  of  the  same 
crystalline  rocks,  and  claimed  that  the  whole  of  the  division 
was  there  represented,  including  the  Potsdam,  the  Hudson 
River  group,  and  the  intermediate  limestones.*  The  conclu- 
sion of  Mather  was  cited  with  approbation  by  Rogers,  who 
apparently  adopted  it,  and  declared  that  Hitchcock  held  a  simi- 
lar view.  It  will  be  seen  that  these  geologists  thus  united ,  in 
one  group  the  schists  of  the  Hoosic  range  (regarded  by  Em- 
mons as  primary)  with  those  of  the  Taconic  range,  and  referred 
both  to  the  age  of  the  Champlain  division,  the  whole  of  which 
was  supposed  .to  be  included  in  the  group. 

In  the  same  address  Professor  Rogers  raised  a  very  important 
question.  Having  referred  to  the  Potsdam  sandstone,  which 
on  Lake  Champlain  forms  the  base  of  the  palaeozoic  system,  he 
inquires,  "  Is  this  formation,  then,  the  lowest  limit  of  our  Ap- 
palachian masses  generally,  or  is  the  system  expanded  down- 
ward in  other  districts  by  the  introduction  beneath  it  of  other 
conformable  sedimentary  rocks  ? "  He  then  proceeded  to  state 
that  from  the  Susquehanna  River,  southwest  ward,  a  more  com- 
plex series  appears  at  the  base  of  the  lower  limestone  than  to 
the  north  of  the  Schuylkill,  and  in  some  parts  of  the  Blue 

*  Geology  of  the  Southern  District  of  New  York,  p.  438. 


XIIL]  GEOGNOSY  OF  THE  APPALACHIANS.  255 

Ridge  he  includes  in  the  primal  division  (beneath  the  Calcifer- 
ous  sand-rock)  "  at  least  four  independent  and  often  very  thick 
deposits,  constituting  one  general  group,  in  which  the  Potsdam 
or  white  sandstone  (with  Scolithus)  is  the  second  in  descending 
order."  This  sandstone  is  overlaid  by  many  hundred  feet  of 
arenaceous  and  ferriferous  fucoidal  slate,  and  underlaid  by 
coarse  sandy  shales  and  flagstones ;  below  which,  in  Virginia 
and  East  Tennessee,  is  a  series  of  heterogeneous  conglomerates, 
which  rest  on  a  great  mass  of  crystalline  strata.  The  accuracy 
of  these  statements  is  confirmed  by  Safford,  who,  in  his  report 
on  the  geology  of  Tennessee  (1869),  places  at  the  base  of  the 
column  a  great  series  of  crystalline  schists,  apparently  repre- 
sentatives of  those  of  southeastern  Pennsylvania.  (Ante,  page 
245.)  Upon  these  repose  what  Safford  designates  as  the  Pots- 
dam group,  including,  in  ascending  order,  the  Ocoee  slates  and 
conglomerates,  estimated  at  10,000  feet,  and  the  Chilhowee 
shales  and  sandstones,  2,000  feet  or  more,  with  fucoids,  worm- 
burrows,  and  Scolithus.  These  are  conformably  overlaid  by 
the  Knoxville  division,  consisting  of  fucoidal  sandstones,  shales, 
and  limestones,  the  latter  two  holding  fossils  of  the  age  of  the 
Calciferous  sand-rock.  It  is  noteworthy  that  these  rocks  are 
greatly  disturbed  by  faults,  and  that  in  Chilhowee  Mountain 
the  lower  conglomerates  are  brought  on  the  east  against  the 
Carboniferous  limestone,  by  a  vertical  displacement  of  at  least 
1 2,000  feet.  The  general  dip  of  all  these  strata,  including  the 
basal  crystalline  schists,  is  to  the  southeast. 

The  primal  palaeozoic  rocks  of  the  Blue  Ridge  were  then  by 
Rogers,  as  now  by  Safford,  looked  upon  as  wholly  of  Potsdam 
age,  including  the  Scolithus  sandstone  as  a  subordinate  member, 
so  that  the  strata  beneath  this  were  still  regarded  as  belong- 
ing to  the  New  York  system.  Hence,  while  Rogers  inquires 
whether  the  Taconic  system  "  may  not  along  the  western  bor- 
der of  Vermont  and  Massachusetts  include  also  some  of  the 
sandy  and  slaty  strata  here  spoken  of  as  lying  beneath  the 
Potsdam  sandstone,"  *  he  would  still  embrace  these  lower 
strata  in  the  Champlain  division. 

*  American  Journal  of  Science  (1),  XLVII.  152,  153. 


256  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

Thus  we  see  that  at  an  early  period  the  rocks  of  the  Taconic 
system  were,  by  Rogers  and  Mather,  referred  to  the  Champlain 
division  of  the  New  York  system,  a  conclusion  which  has  been 
sustained  by  subsequent  observations.  Before  discussing  these, 
and  their  somewhat  involved  history,  we  may  state  two  ques- 
tions which  present  themselves  in  connection  with  this  solu- 
tion of  the  problem.  First,  whether  the  Taconic  system,  as 
denned  by  Emmons,  includes  the  whole  or  a  part  of  the  Cham- 
plain  division ;  and,  second,  whether  it  embraces  any  strata 
older  or  newer  than  the  members  of  this  portion  of  the  New 
York  system.  With  reference  to  the  first  question  it  is  to  be 
remarked,  that  in  their  attempts  to  compare  the  Taconic  rocks 
with  those  of  the  Champlain  division  as  seen  farther  to  the 
west,  observers  were  led  by  lithological  similarities  to  identify 
the  upper  members  of  the  latter  with  certain  portions  of  the 
Taconic.  In  fact,  the  Trenton  limestone,  with  the  Utica 
slates  and  the  Loraine  or  Hudson  River  shales,  making  to- 
gether the  upper  half  of  the  Champlain  division  (in  which 
Emmons,  moreover,  included  the  overlying  Oneida  and  Medina 
conglomerates  and  sandstones),  have  in  New  York  an  aggregate 
thickness  of  not  less  than  three  or  four  thousand  feet,  and  offer 
many  lithological  resemblances  to  the  great  mass  of  sediments 
at  the  western  base  of  the  Green  Mountains,  to  which  the 
name  of  Taconic  had  been  applied.  It  is  curious  to  find  that 
Emmons,  in  1842,  referred  to  the  Medina  the  Red  sand-rock  of 
the  east  shore  of  Lake  Champlain,  since  shown  to  be  Potsdam ; 
and,  moreover,  placed  the  Sillery  sandstone  of  the  neighbor- 
hood of  Quebec  at  the  summit  of  the  Champlain  division,  as 
the  representative  of  the  Oneida  conglomerate ;  while  at  the 
same  time  he  noticed  the  great  resemblance  which  this  sand- 
stone, with  its  adjacent  limestones,  bore  to  similar  rocks  on  the 
confines  of  Massachusetts,  already  referred  by  him  to  the 
Taconic  system.* 

This  view  of  Emmons  as  to  the  Quebec  rocks  was  adopted 
by  Sir  William  Logan,  when,  a  few  years  afterwards,  he  began 
to  study  the  geology  of  that  region.  The  sandstone  of  Sillery 
*  Geology  of  the  Northern  District  of  New  York,  pp.  124,  125. 


XIIL]  GEOGNOSY  OF  THE   APPALACHIANS.  257 

was  described  by  him  as  corresponding  to  the  Oneida  or 
Shawanguiik  conglomerate,  while  the  limestones  and  shales 
of  the  vicinity,  which  were  supposed  to  underlie  it,  were  re- 
garded as  the  representatives  of  the  Trenton,  Utica,  and  Hud- 
son River  formations.*  By  following  these  rocks  along  the 
western  base  of  the  Appalachians  into  Vermont  and  Massa- 
chusetts, they  were  found  to  be  a  continuation  of  the  Taconic 
system,  which  Sir  William  was  thus  led  to  refer  to  the  upper 
half  of  the  Cham  plain  division,  as  had  already  been  done  by 
Professor  Adams  in  1847.t  As  regards  the  crystalline  strata 
of  the  Appalachians  in  this  region,  he,  however,  rejected  the 
view  of  Emmons,  and  maintained  that  put  forward  by  the 
Messrs.  Rogers  in  1841 ;  namely,  that  these,  instead  of  being 
older  rocks,  were  but  these  same  upper  formations  of  the 
Champlain  division  in  an  altered  condition ;  a  view  which  was 
maintained  during  several  years  in  all  of  the  publications  of 
those  connected  with  the  geological  survey  of  Canada. 

This  conclusion,  so  far  as  regards  the  age  of  the  unaltered 
fossiliferous  rocks  from  Quebec  to  Massachusetts,  was  supposed 
to  be  confirmed  by  the  evidence  of  organic  remains  found  in 
them  in  Vermont.  Mr.  Emmons  had  described,  as  character- 
istic of  the  upper  part  of  the  Taconic  system,  two  crustaceans, 
to  which  he  gave  the  names  of  Atops  trilineatus  and  Ellipto- 
cephalus  asaphoides  ;  the  other  fossils  noticed  by  him  being 
graptolites,  fucoids,  and  what  were  apparently  the  marks  of 
annelids.  In  1847  Professor  James  Hall,  in  the  first  volume 
of  his  Paleontology,  declared  the  Atops  of  Emmons  to  be 
identical  with  Triarthrus  (Calymene)  Beddi,  a  characteristic 
fossil  of  the  Utica  slate ;  while  the  Elliptocephalus  was  re- 
ferred by  him  to  the  genus  Olenus,  now  known  to  belong  to 
the  primordial  fauna  of  Sweden,  where  it  is  found  in  slates 
lying  beneath  the  orthoceratite  limestone,  and  near  the  base  of 
the  palaeozoic  series.  Although,  as  it  now  appears,  the  geologi- 
cal horizon  of  the  Olenus  slates  was  well  known  to  Hisinger, 

*  Geological  Survey  of  Canada,  1847-43,  pp.  27,  57  ;  and  American  Jour- 
nal of  Science  (2),  IX.  12. 

t  American  Journal  of  Science  (2),  V.  108. 

Q 


258  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

this  author  in  his  classic  work,  Lethaea  Suecica,  published  in 
1837,  represents,  by  some  unexplained  error,  thes~e  slates  as 
overlying  the  orthoceratite  limestone,  which  is  the  equivalent 
of  the  Trenton  limestone  of  the  Champlain  division.  Hence, 
as  Mr.  Barrande  has  remarked,  Hall  was  justified  by  the  au- 
thority of  Hisinger's  published  work  in  assigning  to  the  Olenus 
slates  of  Vermont  a  position  above  that  limestone,  and  in  placing 
them,  as  he  then  did,  on  the  horizon  of  the  Hudson  River  or 
Loraine  shales.  The  double  evidence  afforded  by  these  two 
f  jssil  forms  in  the  rocks  of  Vermont  served  to  confirm  Sir 
William  Logan  in  placing  in  the  upper  part  of  the  Champlain 
division  the  rocks  which  he  regarded  as  their  stratigraphical 
equivalents  near  Quebec ;  and  which,  as  we  have  seen,  had 
some  years  before  been  by  Emmons  himself  assigned  to  the 
same  horizon.  The  remarkable  compound  graptolites  which 
occur  in  the  shales  of  Pointe  Levis,  opposite  Quebec,  were 
described  by  Professor  James  Hall  in  the  report  of  the  Geo- 
logical Survey  of  Canada  for  1857,  and  were  then  referred  to 
the  Hudson  Eiver  group;  nor  was  it  until  August,  1860,  that 
Mr.  Billings  described  from  the  limestones  of  this  same  series 
at  Pointe  Levis  a  number  of  trilobites,  among  which  were  sev- 
eral species  of  Agnostus,  Dikelocephalus,  Bathyurus,  etc.,  con- 
stituting a  fauna  whose  geological  horizon  he  decided  to  be  in 
the  lower  part  of  the  Champlain  division. 

Just  previous  to  this  time,  in  the  report  of  the  Regents  of 
the  University  of  New  York  for  1859,  Professor  Hall  had 
described  and  figured  by  the  name  of  Olenus  two  species  of 
trilobites  from  the  slates  of  Georgia,  Vermont,  which  Emmons 
had  wrongly  referred  to  the  genus  Paradoxides.  They  were  at 
once  recognized  by  Barrande,  who  called  attention  to  their 
primordial  character,  and  thus  led  to  a  knowledge  of  their  true 
stratigraphical  horizon,  and  to  the  detection  of  the  singular 
error  in  Hisinger's  book,  already  noticed,  by  which  American 
geologists  had  been  misled.*  They  have  since  been  separated 
from  Olenus,  and  by  Professor  Hall  referred  to  a  new  and 

*  For  the  correspondence  on  this  matter  between  Barrande,  Logan,  and 
Hall,  see  American  Journal  of  Science  (2),  XXXI.  210-226. 


XIII.]  GEOGNOSY  OF  THE  APPALACHIANS.  259 

closely  related  genus,  which  he  has  named  Olenellus,  and  which 
is  now  regarded  as  belonging  to  the  horizon  of  the  Potsdam 
sandstone,  to  which  we  shall  presently  advert. 

Further  studies  of  the  fossiliferous  rocks  near  Quebec  showed 
the  existence  of  a  mass  of  sediments  estimated  at  about  1,200 
feet,  holding  a  numerous  fauna,  and  corresponding  to  a  great 
development  of  strata  about  the  age  of  the  Calciferous  and 
Chazy  formations,  or,  more  exactly,  to  a  formation  occupying  a 
position  between  these  two,  and  constituting,  as  it  were,  beds 
of  passage  between  them.  In  this  new  formation  were  in- 
cluded the  graptolites  already  described  by  Hall,  and  the 
numerous  Crustacea  and  brachiopoda  described  by  Billings,  all 
of  which  belong  to  the  Levis  slates  and  limestones.  To  these 
and  their  associated  rocks  Sir  William  Logan  then  gave  the 
name  of  the  Quebec  group,  including,  besides  the  fossiliferous 
Levis  formation,  a  great  mass  of  overlying  slates,  sandstones, 
and  magnesian  limestones,  hitherto  without  fossils,  which  have 
been  named  the  Lauzon  rocks,  and  the  Sillery  sandstones  and 
shales,  which  he  supposed  to  form  the  summit  of  the  group, 
and  which  had  afforded  only  an  Obolella  and  two  species  of 
Lingula ;  *  the  volume  of  the  whole  group  being  about  7,000 
feet. 

The  paleontological  evidence  thus  obtained  by  Billings  and 
by  Hall,  both  from  near  Quebec  and  in  Vermont,  led  to  the 
conclusion  that  the  strata  of  these  regions,  so  much  resembling 
the  upper  members  of  the  Champlain  division,  were  really  a 
great  development,  in  a  modified  form,  of  some  of  its  lower  por- 
tions. Their  apparent  stratigraphical  relations  were  explained 
by  Logan  by  the  supposition  of  "  an  overturned  anticlinal  fold, 
with  a  crack  and  a  great  dislocation  running  along  the  summit, 
by  which  the  Quebec  group  is  brought  to  overlie  the  Hudson 
River  group.  Sometimes  it  may  overlie  the  overturned  Utica 
formation,  and  in  Vermont  points  of  the  overturned  Trenton 
appear  occasionally  to  emerge  from  beneath  the  overlap."  He, 
at  the  same  time,  declared  that  "  from  the  physical  structure 
alone,  no  person  would  suspect  the  break  that  must  exist  in 

*  See  Billings,  Palaeozoic  Fossils  of  Canada,  p.  69. 


260  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

the  neighborhood  of  Quebec,   and,  without  the  evidence  of 
fossils,  every  one  would  be  authorized  to  deny  it."  * 

The  rocks  from  western  Vermont,  which  had  furnished  to 
Hall  the  species  of  Olenellus,  have  long  been  known  as  the 
Red  sand-rock,  and,  as  we  have  seen,  were  by  Emmons,  in  1842, 
referred  to  the  age  of  the  Medina  sandstone,  —  a  view  which 
the  late  Professor  Adams  still  maintained  as  late  as  1847.f  In 
the  mean  time  Emmons  had,  in  1855,  declared  this  rock  to 
represent  the  Calciferous  and  Potsdam  formations,  the  brown 
sandstones  of  Burlington  and  Charlotte,  Vermont,  being  re- 
ferred to  the  latter.  J  This  conclusion-  was  confirmed  by 
Billings,  who,  in  1861,  after  visiting  the  region  and  examin- 
ing the  organic  remains  of  the  Red  sand-rock,  assigned  to  it  a 
position  near  the  horizon  of  the  Potsdam.  §  Certain  trilobites 
found  in  this  Red  sand-rock  by  Adams,  in  1847,  were  by  Hall 
recognized  as  belonging  to  the  European  genus  Conocephalus 
(=  Conocephalites  and  Conocoryphe],  whose  geological  horizon 
was  then  undetermined.  ||  The  formation  in  question  consists 
in  great  part  of  a  red  or  mottled  granular  dolomite,  associated 
with  beds  of  fucoidal  sandstone,  conglomerates,  and  slates. 
These  rocks  were  carefully  examined  by  Logan  in  Swanton, 
Vermont,  where,  according  to  him,  they  have  a  thickness  of 
2,200  feet,  and  include  toward  their  base  a  mass  of  dark- 
colored  shales  holding  Olenellus  with  Conocephalites,  Obolella, 
etc. ;  Conocephalites  Teucer,  Billings,  being  common  to  the 
shales  and  the  red  sandy  beds.  IF  Many  of  these  fossils  are 
also  found  at  Troy  and  at  Bald  Mountain,  New  York,  where 
they  accompany  the  At  ops  of  Emmons,  now  recognized  by 
Billings  as  a  species  of  Conocephalites. 

*  Logan's  letter  to  Barrande,  American  Journal  of  Science  (2),  XXXI.  218. 
The  time  date  of  this  letter  was  December  31,  1860,  but,  by  a  misprint,  it  is 
made  1831. 

t  Adams,  American  Journal  of  Science  (2),  V.  108. 

£  Emmons,  American  Geology,  II.  128. 

§  American  Journal  of  Science  (2),  XXXII.  232. 

II  Ibid.  (2),  XXXIII.  374. 

IT  Geology  of  Canada,  1863,  p.  281 ;  American  Journal  of  Science  (2), 
XLVI.  224. 


XIII.]  GEOGNOSY  OF  THE  APPALACHIANS.  2G1 

A  similar  condition  of  things  extends  northeastward  along 
the  Appalachian  region.  On  the  south  side  of  the  St.  Law- 
rence below  Quebec  a  great  thickness  of  limestones,  sandstones, 
and  slates,  formerly  referred  to  the  Quebec  group,  is  now  re- 
garded by  Billings  as,  in  part  at  least,  of  the  Potsdam  forma- 
tion ;  while  on  the  coast  of  Labrador  and  in  northern  New- 
foundland the  same  formation,  characterized  by  the  same  fossils 
as  in  Vermont,  is  largely  developed,  attaining  in  some  parts, 
according  to  Murray,  a  thickness  of  3,000  feet  or  more.  Along 
the  northern  coast  of  the  island  it  is  nearly  horizontal,  and 
appears  to  be  conformably  overlaid  by  about  4,000  feet  of 
fossiliferous  strata  representing  the  Calciferous  sand-rock  and 
the  succeeding  Levis  formation. 

Mr.  Billings  has  described  a  section  from  the  Laurentian  of 
Crown  Point,  New  York,  to  Cornwall,  Vermont,  from  which  it 
appears  that  to  the  eastward  of  a  dislocation  which  brings  up 
the  Potsdam  to  overlie  the  higher  members  of  the  Champlain 
division,  the  Potsdam  is  itself  overlaid,  at  a  small  angle,  by  a 
great  mass  of  limestones  representing  the  Calciferous,  and  hav- 
ing at  the  summit  some  of  the  characteristic  fossils  of  the 
Levis  formation.  Next  in  ascending  order  are  not  less  than 
2,000  feet  of  limestones  with  Trenton  fossils  (embracing  prob- 
ably the  Chazy  division),  while  to  the  east  of  this  the  Levis 
again  appears,  including  the  white  Stockbridge  limestones.* 
We  have  here  an  evidence  that  the  augmentation  in  volume 
observed  in  the  lower  members  of  the  Champlain  division  in 
the  Appalachian  region  extends  to  the  Trenton,  which  to  the 
west  of  Lake  Champlain  is  represented,  the  Chazy  included, 
by  not  more  than  500  feet  of  limestone.  The  Potsdam,  in  the 
latter  region,  consists  of  from  500  to  700  feet  of  sandstone 
holding  Conocephalites  and  Lingulella,  and  overlaid  by  300 
feet  of  magnesian  limestone,  the  so-called  Calciferous  sand-rock. 
In  the  valley  of  the  Mississippi  these  two  formations  in  Iowa, 
Missouri,  and  Texas  are  represented  by  from  800  to  1,300  feet  of 
sandstones  and  magnesian  limestones  ;  while  in  the  Black  Hills 

*  T.  S.  Hunt  on  the  Geology  of  Vermont,  American  Journal  of  Science 
(2),  XLVI.  227. 


262  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

of  Nebraska,  according  to  Hayden,  the  only  representative  of 
these  lower  formations  is  about  one  hundred  feet  of  sandstone 
holding  Potsdam  fossils.* 

In  striking  contrast  to  this,  it  has  been  shown  that  along  the 
Appalachian  range  from  Newfoundland  to  Tennessee  these 
lower  formations  are  represented  by  from  8,000  to  15,000  feet 
of  fossiliferous  sediments.  It  has  been  suggested  by  Logan 
that  these  widely  differing  conditions  represent  deep-sea  accu- 
mulations on  the  one  hand,  and  the  deposits  from  a  shallow 
sea  which  covered  a  submerged  continental  plateau  on  the 
other ;  the  sediments  in  the  two  areas  being  characterized  by  a 
similar  fauna,  though  differing  greatly  in  lithological  characters 
and  in  thickness.  To  this  we  may  add,  that  the  continental 
area,  being  probably  submerged  and  elevated  at  intervals,  be- 
came overlaid  with  beds  which  represent  only  in  a  partial  and 
imperfect  manner  the  great  succession  of  strata  which  were 
being  accumulated  in  the  adjacent  ocean,  t 

In  a  paper  which  I  hope  to  present  to  the  geological  section 
during  the  present  meeting  of  the  Association,  it  will  be  shown, 
from  a  study  of  the  rocks  of  the  Ottawa  basin,  that  the  typical 
Champlain  division  not  only  presents  important  paleontological 
breaks,  but  evidences  of  stratigraphical  discordance  at  more 

*  American  Journal  of  Science  (2),  XXV.  439;  XXXI.  234.  [Later  obser- 
vations show  great  variations  in  the  thickness  of  these  lower  rocks  in  the  West. 
In  the  Wahsatch  Mountains  are  found,  according  to  Bradley,  from  1,500  to 
2,000  feet  of  sandstones  and  conglomerates,  regarded  as  Potsdam,  overlaid  by 
3,000  feet  of  magnesian  limestones  and  shales,  holding  fossils  of  the  Levis, 
and,  towards  the  summit,  of  Niagara  and  probably  of  Lower  Helderberg 
age  ;  the  whole  followed  by  2,000  feet  of  Devonian  sandstones  and  3,000 
feet  of  Carboniferous  limestones.  In  the  Teton  Mountains,  however,  accord- 
ing to  the  same  observer,  this  great  thickness  of  Potsdam  and  Levis  rocks  is 
represented  by  only  700  feet  of  quartzites  and  limestones,  overlaid  by  about 
600  feet  of  magnesian  limestones,  probably  of  Niagara  age,  followed  by  2,000 
feet  of  Carboniferous  limestones.  In  the  Wind  River  Mountains,  in  western 
Wyoming,  Professor  Comstock  has  described  a  remarkable  series,  including 
Potsdam  and  Levis,  followed  by  strata  of  Oriskany  age,  Carboniferous  lime- 
stones, Triassic,  Jurassic,  and  Cretaceous  rocks,  all  apparently  conformable, 
and  resting  at  an  angle  of  about  20°  on  the  crystalline  Eozoic  rocks.  Re- 
mains of  the  fauna  of  the  Trenton  period  (Upper  Cambrian)  have  moreover 
very  recently  been  made  known  to  us  from  the  West.  ] 

t  Ibid.  (2),  XLVI.  225. 


XIIL]  GEOGNOSY  OF  THE  APPALACHIANS.  263 

than  one  horizon  over  the  continental  area,  which,  as  the  result 
of  widely  spread  movements,  might  be  supposed  to  be  repre- 
sented in  the  Appalachian  region.  In  the  latter  Logan  has 
already  observed  that  the  absence  of  all  but  the  highest  beds 
of  the  Levis  along  the  eastern  limit  of  the  Potsdam,  near 
Swanton,  Vermont  (while  the  whole  thickness  of  them  ap- 
pears a  little  farther  westward),  makes  it  probable  that  there 
is  a  want  of  conformity  between  the  two ;  and  I  have  in 
this  connection  insisted  upon  the  entire  absence,  in  this 
locality,  of  the  Calciferous,  which  is  met  with  a  little  farther 
south  in  the  section  just  mentioned,  as  another  evidence  of 
the  same  unconformity.*  There  are  also,  I  think,  reasons 
for  suspecting  another  stratigraphical  break  at  the  summit 
of  the  Quebec  group,t  in  which  case  many  problems  in 
the  geological  structure  of  this  region  will  be  much  sim- 
plified. 

It  should  be  remembered  that  the  conditions  of  deposition 
in  some  areas  have  been  such  that  accumulations  of  strata,  cor- 
responding to  long  geologic  periods,  and  elsewhere  marked  by 
stratigraphical  breaks,  are  arranged  in  conformable  superposi- 
tion ;  and  moreover  that  movements  of  elevation  and  depres- 
sion have  even  caused  great  paleontological  breaks,  which  over 
considerable  areas  are  not  marked  by  any  apparent  discordance. 
Thus  the  remarkable  break  in  the  fauna  between  the  Calcifer- 
ous and  the  Chazy  is  not  accompanied  by  any  noticeable  dis- 
cordance in  the  Ottawa  basin ;  and  in  Nebraska,  according  to 
Hayden,  the  Potsdam,  Carboniferous,  Jurassic,  and  Cretaceous 
formations  are  all  represented  in  about  1,200  feet  of  conforma- 
ble strata.  J  In  Sweden  the  whole  series  from  the  base  of  the 
Cambrian  to  the  summit  of  the  Silurian  appears  as  a  conform- 
able sequence,  while  in  North  Wales,  although  there  is  no  ap- 
parent discordance  from  the  base  of  the  Cambrian  to  the  sum- 
mit of  the  Lingula  flags,  stratigraphical  breaks,  according  to 
liamsay,  probably  occur  both,  at  the  base  and  the  summit 

*  American  Journal  of  Science  (2),  XLVI.  225. 

•f-  See,  for  the  evidence  of  this,  Essay  XV.,  Part  Third. 

J  American  Journal  of  Science  (2),  XXV.  440. 


264'  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

of  the  Tremadoc  slates,*  which  are  considered  equivalent  to 
the  Levis  formation. 

We  have  seen  that,  according  to  Logan,  a  dislocation  a  little 
;to  the  north  of  Lake  Champlain  causes  the  Quebec  group  to 
overlie  the  higher  members  of  the  Champlain  division.  The 
same  uplift,  according  to  him,  brings  up,  farther  south,  the 
Red  sand-rock  of  Vermont,  which  to  the  west  of  the  disloca- 
tion rests  upon  the  upturned  and  inverted  strata  of  various 
formations  from  the  Calciferous  sand-rock  to  the  Utica  and 
Hudson  River  shales.  These  latter,  according  to  him,  are  seen 
to  pass  for  considerable  distances  beneath  nearly  horizontal 
layers  of  the  Red  sand-rock,  the  Utica  slate,  in  one  case,  hold- 
ing its  characteristic  fossil,  Triarthrus  Beckii.  This  relation, 
which  is  well  shown  in  a  section  at  St.  Albans,  figured  by 
Hitchcock,  t  was  looked  upon  by  Emmons  and  by  Adams  as 
evidence  that  the  Red  sand-rock  was  the  representative  of  the 
Medina  sandstone  of  the  New  York  system.  When,  however, 
the  former  had  recognized  the  Potsdam  age  of  the  sand-rock, 
with  its  Olenellus,  which  he  supposed  to  be  Paradoxides,  this 
condition  of  things  was  conceived  to  be  an  evidence  of  the 
existence  beneath  the  Potsdam  of  an  older  and  unconformable 
fossiliferous  series  already  mentioned. 

The  objections  made  by  Emmons  to  Rogers's  view  of  the 
Champlain  age  of  the  Taconic  rocks  were  threefold  :  first,  the 
great  differences  in  lithological  characters,  succession,  and  thick- 
ness between  these  and  the  rocks  of  the  Champlain  division 
as  previously  known  in  New  York ;  second,  the  supposed  un- 
conformable infraposition  of  a  fossiliferous  series  to  the  Pots- 
dam ;  and,  third,  the  distinct  fauna  which  the  Taconic  rocks 
were  supposed  to  contain.  The  first  of  these  is  met  by  the 
fact,  now  established,  that,  in  the  Appalachian  region,  the  Cham- 
plain  division  is  represented  by  rocks  having,  with  the  same 
organic  remains,  very  different  lithological  characters,  and  a 
thickness  tenfold  greater  than  in  the  typical  Champlain  region 
«of  northern  New  York.  The  second  objection  has  already 

*  Quar.  Geol.  Journal,  XIX.  p.  36. 
f  Geology  of  Vermont,  p.  374. 


XIII.  ]  GEOGNOSY  OF  THE  APPALACHIANS.  ?265 

been  answered  by  showing  that  the  rocks  which,  as  in  the  St. 
Albans  section,  pass  beneath  the  Potsdam  are  really  newer 
strata  belonging  to  the  upper  part  of  the  division,  and  contain 
a  characteristic  fossil  of  the  Utica  slate.  As  to  the  third  point, 
it  has  also  been  met,  so  far  as  regards  the  Atops  and  Ellipto- 
cephalus,  by  showing  these  two  genera  to  belong  to  the  Pots- 
dam formation.  If  we  inquire  further  into  the  Taconic  fauna, 
we  find  that  the  Stockbridge  limestone  (the  Eolian  limestone 
of  Hitchcock),  which  was  placed  by  Emmons  near  the  base  of 
the  Lower  Taconic  (while  the  Olenellus  slates  are  near  the  sum- 
mit of  the  Upper  Taconic),  is  also  fossiliferous,  and  contains, 
according  to  the  determinations  of  Professor  Hall,  species  be- 
longing to  the  genera  Euomphalus,  Zaphrentis,  Stroinatopora, 
Chaetetes,  and  Stictopora.*  Such  a  fauna  would  lead  to  the 
conclusion  that  these  limestones,  instead  of  being  older,  were 
really  newer  than  the  Olenellus  beds,  and  that  the  apparent 
order  of  succession  was,  contrary  to  the  supposition  of  Em- 
mons, the  true  one.  This  conclusion  was  still  further  confirmed 
by  the  evidence  obtained  in  1868  by  Mr.  Billings,  who  found 
in  that  region  a  great  number  of  characteristic  species  of  the 
Levis  formation,  many  of  them  in  beds  immediately  above  or 
below  the  white  marbles,t  which  latter,  from  the  recent  obser- 
vations of  the  Rev.  Augustus  Wing,  in  the  vicinity  of  Rutland, 
Vermont,  would  seem  to  be  among  the  upper  beds  of  the  Pots- 
dam formation.  Thus  while  some  of  the  Taconic  fossils  belong 
to  the  Potsdam  and  Utica  formations,  the  greater  number  of 
them,  derived  from  beds  supposed  to  be  low  down  in  the  sys- 
tem, are  shown  to  be  of  the  age  of  the  Levis  formation.  There 
is,  therefore,  at  present,  no  evidence  of  the  existence,  among 
the  unaltered  sedimentary  rocks  of  the  western  base  of  the 
Appalachians  in  Canada  or  New  England,  of  any  strata  more 
ancient  than  those  of  the  Champlain  di vision,  J  to  which,  from 

»  Geology  of  Vermont,  419 ;  and  American  Journal  of  Science  (2),  XXXIII. 
419. 

t  American  Journal  of  Science  (2),  XLVI.  227. 

£  See,  on  this  point  and  on  the  possibly  greater  antiquity  of  the  rocks 
called  Potsdam,  Essay  XV.,  Part  Third. 
12 


266  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

their  organic  remains,  the  fossiliferous  Taconic  rocks  are  shown 
to  belong. 

Mr.  Billings  has,  it  is  true,  distinguished  provisionally  what 
he  has  designated  an  upper  and-  a  lower  division  of  the  Pots- 
darn,  and  has  referred  to  the  latter  the  Red  sand-rock  with  the 
Olenellus  slates  of  Vermont,  together  with  beds  holding  similar 
fossils  at  Troy,  New  York,  and  along  the  Strait  of  Bellisle  in 
Labrador  and  Newfoundland ;  the  upper  division  of  the  Pots- 
dam being  represented  by  the  basal  sandstones  of  the  Ottawa 
basin  and  of  the  Mississippi  valley.*  In  the  present  state  of 
our  knowledge  of  the  local  variations  in  sediments  and  in  their 
fauna  dependent  on  depth,  temperature,  and  ocean  currents, 
Billings,  however,  conceives  that  it  would  be  premature  to  assert 
that  these  two  types  of  the  Potsdam  do  not  represent  syn- 
chronous deposits. 

The  base  of  the  Champlain  division,  as  known  in  the  Pots- 
dam formation  of  New  York,  of  the  Mississippi  valley,  and 
the  Appalachian  belt,  does  not,  however,  represent  the  base  of 
the  paleozoic  series  in  Europe.  The  Alum  slates  in  Sweden 
are  divided  into  two  parts,  an  upper  or  Olenus  zone,  and  a 
lower  or  Conocoryphe  zone,  as  distinguished  by  Angelin.  The 
latter  is  characterized  by  the  genus  Paradoxides,  which  also 
occupies  a  lower  division  in  the  primordial  palseozoic  rocks  of 
Bohemia  (Barrande's  stage  C),  the  greater  part  of  which  are 
regarded  as  the  equivalent  of  the  Olenus  zone  of  Sweden  and 
the  Potsdam  of  North  America.  The  Lingula  flags  of  Wales 
belong  to  the  same  horizon,  and  it  is  at  their  base,  in  strata 
once  referred  to  the  Lower  Lingula  flags,  that  the  Paradoxides 
is  met  with.  These  strata,  for  which  Hicks  and  Salter,  in 
1865,  proposed  the  name  of  the  Menevian  group,  are  regarded 
as  corresponding  to  the  lower  division  of  the  Alum  slates,  and, 
like  it,  contain  a  fauna  not  yet  recognized  in  the  basal  rocks  of 
the  New  York  system.  [Beneath  the  Menevian  lie  the  Llan- 
beris  and  Harlech  rjcks  (the  Longmynd),  which  constitute  the 
Lower  Cambrian  of  Sedgwick ;  while  above  it  are  the  great 
mass  of  the  Lingula  flags  and  the  Tremadoc  rocks,  his  Middle 

*  Report  Geol.  of  Canada,  1863-66,  p.  236. 


XIII.]  GEOGNOSY  OF  THE  APPALACHIANS.  267 

Cambrian,  To  these  succeed  the  Bala  or  Upper  Cambrian, 
the  equivalent  of  the  Llandeilo  and  Caradoc  rocks,  to 
wliich  Murchison  gave  the  name  of  Lower  Silurian.  He  at 
first  claimed  the  Llandeilo  as  the  base  of  his  Silurian  system, 
but  subsequently  endeavored  to  extend  it  downwards  so  as  to 
include,  under  the  name  of  Primordial  Silurian,  the  Middle 
Cambrian  of  Sedgwick.  To  this  Lyell  objected,  and  while 
conceding  to  Murchison  the  Upper  Cambrian  as  Lower  Silu- 
rian, gave  to  the  middle  division  of  Sedgwick's  series  the 
name  of  Upper  Cambrian.  Hicks  in  a  recent  paper  (1873) 
has  adopted  a  similar  compromise,  including,  however,  in  the 
Lower  Silurian  the  Arenig  group,  and  making  the  Tremadoc 
the  upper  member  of  the  Upper  Cambrian.  For  a  discussion 
of  the  relations  of  Cambrian  and  Silurian  the  reader  is  re- 
ferred to  Essay  XV.  in  this  volume.]  The  same  classification 
is  now  adopted  by  Linarsson,  in  Sweden,  where,  in  Westro- 
gothia,  the  Cambrian  rocks  (resting  unconformably  on  the 
crystalline  schists  to  be  noticed  further  on)  are  overlaid  con- 
formably by  the  orthoceratite-limestones,  which  are  by  him 
regarded  as  forming  the  base  of  the  Silurian,  and  as  the  equiva- 
lent of  the  Llandeilo  rocks  of  Wales.  The  total  thickness  of 
these  lower  rocks  in  Sweden,  including  the  representatives 
of  the  Lingula  flags,  the  Menevian  beds,  and  an  underlying 
fucoidal  (Eophyton)  sandstone,  is  only  three  hundred  feet, 
while  the  first  two  divisions  in  Wales  have  a  thickness  of  five 
to  six  thousand,  and  the  Harlech  grits  and  Llanberis  slates 
(including  the  Welsh  roofing-slates  beneath)  amount  to  eight 
thousand  feet  additional.  Recent  researches  show  that  these 
lower  rocks  in  Wales  contain  an  abundant  fauna,  extending 
downward  some  2,800  feet  from  the  Menevian  to  the  very 
base  of  strata  regarded  as  the  representatives  of  the  Harlech 
grits.  The  brachiopoda  of  the  Harlech  beds  appear  identical 
with  those  of  the  Menevian,  but  new  species  of  Conocephalites, 
Microdiscus,  and  Paradoxides  are  met  with,  besides  a  new 
genus,  Plutonia,  allied  to  the  last  mentioned.*  [The  Upper 

*  Hicks,  Geol.  Ma?.,  V.  306  ;    and  Rep.  Brit.  Assoc.,  1868,  p.  69  ;   also 
Harkness  and  Hicks  in  Nature,  Proc.  Geol.  Soc.,  May  10,  1871. 


268  GEOGNOSY   OF   THE   APPALACHIANS.  [XIII. 

Cambrian,  as  defined  by  Sedgwick,  is  represented  in  North 
America  by  the  upper  portion  of  the  Champlain  division  of 
New  York,  from  the  top  of  the  Chazy,  while  the  Middle  and 
Lower  Cambrian  have  their  equivalents  in  the  Quebec  group, 
the  Chazy,  Calciferous,  and  Potsdam,  and  in  the  strata  holding 
Paradoxides  and  other  primordial  forms  in  Massachusetts,  New 
Brunswick,  and  Newfoundland.  The  precise  relation  of  these 
to  the  Potsdam  formation  of  New  York  is  yet  to  be  deter- 
mined, as  well  as  the  question  whether  there  exists  in  the 
Appalachians  any  palaeozoic  rocks  belonging  to  a  lower  horizon 
than  the  Potsdam.  For  a  further  discussion  of  these  questions 
the  reader  is  referred  to  Essay  XV.  in  the  present  volume.] 

In  May,  1861,  I  called  attention  to  the  fact  that  beds  of 
quartzose  conglomerate  at  the  base  of  the  Potsdam  in  Hem- 
mingford,  near  the  outlet  of  Lake  Champlain,  on  its  western 
side,  contain  fragments  of  green  and  black  slates,  "  showing  the 
existence  of  argillaceous  slates  before  the  deposition  of  the 
Potsdam  sandstone."  *  The  more  ancient  strata,  which  fur- 
nished these  slaty  fragments  to  the  Potsdam  conglomerate, 
have  perhaps  been  destroyed,  or  are  concealed,  but  they  or 
their  equivalents  may  yet  be  discovered  in  some  part  'of  the 
great  Appalachian  region.  They  should  not,  however,  be 
called  Taconic,  but  receive  the  prior  designation  of  Cambrian, 
unless,  indeed,  it  shall  appear  that  the  source  of  these  slate 
fragments  was  the  more  argillaceous  beds  of  the  still  older 
Huronian  schists.  Emmons  regarded  his  Taconic  system  as 
the  equivalent  of  the  Lower  (and  Middle)  Cambrian  of  Sedg- 
wick ;  but  when,  in  1 842,  Murchison  announced  that  the  name 
of  Cambrian  had  ceased  to  have  any  zoological  significance, 
being  identical  with  Lower  Silurian,  t  Emmons,  conceiving,  as 
he  tells  us,  that  all  Cambrian  rocks  were  not  Silurian,  instead 
of  maintaining  Sedgwick's  name  which,  with  the  progress  of 
paleontological  study,  is  assuming  a  great  zoological  importance, 
devised  the  name  of  Taconic,  as  synonymous  with  the  Lower 
(arid  Middle)  Cambrian  of  Sedgwick.  J 

*  American  Journal  of  Science  (2),  XXXI.  404. 
t  Proc.  Geol.  Soc.  London,  III.  642. 

t  Emmoris,  Geol.  N.  District  of  New  York,  162  ;  and  Agric.  of  New  York, 
I.  49. 


XIIL]  GEOGNOSY  OF  THE  APPALACHIANS.  269 

The  crystalline  strata  to  which  the  name  of  the  Huronian 
series  has  been  given  by  the  Geological  Survey  of  Canada,  have 
sometimes  been  called  Cambrian  from  their  resemblance  to  cer- 
tain crystalline  rocks  in  Anglesea,  which  have  been  imagined 
to  be  altered  Cambrian.  The  typical  Cambrian  rocks  of  Wales, 
down  to  their  base,  are,  however,  uncrystalline  sediments,  and, 
as  pointed  out  by  Dr.  Bigsby  in  1863,*  are  not  to  be  confounded 
with  the  Huronian,  which  he  regarded  as  equivalent  to  the 
second  division  of  the  so-called  azoic  rocks  of  Norway,  the 
Urschiefer  or  primitive  schists,  which  in  that  country  rest  un- 
conformably  on  the  primitive  gneiss  (Urgneiss),  and  are  in  their 
turn  overlaid  unconformably  by  the  fossiliferous  Cambrian 
strata.  This  second  or  intermediate  series  in  Norway  is  char- 
acterized by  eurites,  micaceous,  chloritic,  and  hornblendic 
schists,  with  diorites,  steatite,  and  dark-colored  serpentines, 
generally  associated  with  chrome ;  and  abounds  in  ores  of  cop- 
per, nickel,  and  iron.  In  its  mineralogical  and  lithological 
characters,  the  Urschiefer  corresponds  with  what  we  have 
designated  the  second  series  of  crystalline  schists.  It  is,  in 
Norway,  divided  into  a  lower  or  quartzose  division,  marked  by 
a  predominance  of  quartzites,  conglomerates  and  more  massive 
rocks,  and  an  upper  and  more  schistose  division.  Macfarlane, 
who  was  familiar  with  the  rocks  of  Norway,  after  examining 
both  the  Huronian  of  Lake  Superior  and  the  crystalline  strata 
of  the  Green  Mountains,  had  already,  in  1862,  declared  his 
opinion  that  both  of  these  were  representatives  of  the  Nor- 
wegian Urschiefer,t  thus  anticipating,  from  his  comparative 
studies,  the  conclusions  of  Bigsby. 

The  crystalline  rocks  of  Anglesea  and  the  adjacent  part  of 
Caernarvon,  which  have  been  described  and  mapped  by  the 
British  Geological  Survey  as  altered  Cambrian,  are  directly 
overlaid  by  strata  of  the  Llandeilo  or  Upper  Cambrian  division, 
corresponding  to  the  Trenton  and  Hudson  River  formations. 
If  we  consult  Eamsay's  report  on  the  region,  it  will  be  found 
that  he  speaks  of  the  lower  rocks  as  "  probably  Cambrian," 

*  Quar.  Jour.  Geol.  Soc.,  XIX.  36. 
f  Canadian  Naturalist,  VII.  125. 


270  GEOGNOSY   OF  THE  APPALACHIANS.  [XIII. 

and  states  as  a  reason  for  that  opinion,  that  they  are  connected 
by  certain  beds  of  intermediate  lithological  characters  with 
strata  of  undoubted  Cambrian  age.*  These,  however,  as  he 
admits,  present  great  local  variations,  and,  after  carefully  scan- 
ning the  whole  of  the  evidence  adduced,  I  am  inclined  to  see 
in  it  nothing  more  than  the  existence,  in  this  region,  of  Cam- 
brian strata  made  up  from  the  ruins  from  the  great  mass  of 
pre-Cambrian  schists,  which  are  the  crystalline  rocks  of  Angle- 
sea.  Such  a  phenomenon  is  repeated  in  numerous  instances  in 
our  North  American  rocks,  and  is  the  true  explanation  of  many 
supposed  examples  of  passage  from  crystalline  schists  to  un- 
crystalline  sediments.  The  Anglesea  rocks  are  a  highly  inclined 
and  much  contorted  series  of  quartzose,  micaceous,  chloritic, 
and  epidotic  schists,  with  diorites  and  dark-colored  chromifer- 
ous  serpentines,  all  of  which,  after  a  careful  examination  of 
them  in  the  collections  of  the  Geological  Survey  of  Great 
Britain,  I  consider  identical  with  the  rocks  of  the  Green 
Mountain  or  Huronian  series.  A  similar  view  of  their  age  is 
shared  by  Phillips  and  by  Sedgwick,  in  opposition  to  the 
opinion  of  the  British  survey.  The  former  asserts  that  the 
crystalline  schists  of  Anglesea  are  "  below  all  the  Cambrian 
rocks  "  ;  t  while  Sedgwick  expresses  the  opinion  that  they  are 
of  "  a  distinct  epoch  from  the  other  rocks  of  the  district,  and 
evidently  older."  J 

Associated  with  the  fossiliferous  Devonian  rocks  of  the 
Ehine  is  a  series  of  crystalline  schists,  similar  to  those  just 
noticed,  seen  in  the  Taunus,  the  Hundsriick,  and  the  Ardennes. 
These,  in  opposition  to  Dumont,  who  regarded  them  as  belong- 
ing to  an  older  system,  are  declared  by  Romer  to  have  resulted 
from  a  subsequent  alteration  of  a  portion  of  the  Devonian 
sediments.  § 

Turning  now  to  the  Highlands  of  Scotland,  we  have  a  simi- 
lar series  of  crystalline  schists,  presenting  all  the  mineralogical 

*  Geol.  of  North  Wales,  pp.  145,  175. 

t  Manual  of  Geology  (1855),  89. 

J  Geol.  Journal  for  1845,  449. 

§  Naumann,  Geognosie,  2d  edition,  II.  383. 


XIII.]  GEOGNOSY   OF  THE   APPALACHIANS.  271 

characters  of  those  of  Norway  and  of  Anglesea,  which,  accord- 
ing to  Murchison  and  Giekie,  are  younger  than  the  fossilifer- 
ous  limestones  of  the  western  coast  (about  the  horizon  of  the 
Levis  formation  of  the  Quebec  group),  which  seem  to  pass 
beneath  them.  Professor  Nicol,  on  the  contrary,  maintains 
that  this  apparent  superposition  is  due  to  uplifts,  and  that 
these  crystalline  schists  are  really  older  than  the  lowest  Cam- 
brians, which  appear  to  the  west  of  them  as  uncrystalline  sedi- 
ments resting  on  the  Laurentian.  He  does  not,  however, 
confound  these  crystalline  schists  of  the  Scottish  Highlands 
with  the  Laurentian,  from  which  they  differ  mineralogically, 
but  regards  them  as  a  distinct  series.*  In  the  presence  of  the 
differences  of  opinion  which  have  been  shown  in  this  contro- 
versy, we  may  be  permitted  to  ask  whether,  in  such  a  case, 
stratigraphical  evidence  alone  is  to  be  relied  upon.  Eepeated 
examples  have  shown  that  the  most  skilful  stratigraphists  may 
be  misled  in  studying  the  structure  of  a  disturbed  region 
where  there  are  no  organic  remains  to  guide  them,  or  where 
unexpected  faults  and  overslides  may  deceive  even  the  most 
sagacious.  I  am  convinced  that  in  the  study  of  the  crystalline 
schists,  the  persistence  of  certain  mineral  characters  must  be 
relied  upon  as  a  guide,  and  that  the  language  used  by  Delesse, 
in  1847,  will  be  found  susceptible  of  a  wide  application  to 
crystalline  strata :  "  Rocks  of  the  same  age  have  most  gener- 
ally the  same  chemical  and  mineralogical  composition,  and, 
reciprocally,  rocks  having  the  same  chemical  composition  and 
the  same  minerals,  associated  in  the  same  manner,  are  of  the 
same  age."  t  In  this  connection  the  testimony  of  Professor 
James  Hall  is  also  to  the  point.  Speaking  of  the  crystalline 
schists  of  the  White  Mountain  series,  he  says  :  — 

"  Every  observing  student  of  one  or  two  years'  experience  in 
the  collection  of  minerals  in  the  New  England  States  knows 
well  that  he  may  trace  a  mica-schist  of  peculiar  but  varying 
character  from  Connecticut,  through  central  Massachusetts,  and 

*  Quar.  Jour.  Geol.  Soc. ;  Murchison,  XV.  353  ;  Giekie,  XVII.  171 ;  Nicol, 
XVII.  58,  XVIII.  443.     • 
f  Bull.  Soc.  Gkrol.  de  Fr.  (2),  IV.  786. 


272  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

thence  into  Vermont  and  New  Hampshire,  by  the  presence  of 
staurolite  and  some  other  associated  minerals,  which  mark  with 
the  same  unerring  certainty  the  geological  relations  of  the  rock 
as  the  presence  of  Pentamerus  oblongus,  P.  galeatus,  Spirifer 
Niayarensis,  or  S.  macropleura,  and  their  respectively  asso- 
ciated fossils,  do  the  relations  of  the  several  rocks  in  which 
these  occur."  * 

I  am  convinced  that  these  crystalline  schists  of  Germany, 
Anglesea,  and  the  Scotch  Highlands  will  be  found,  like  those 
of  Norway,  to  belong  to  a  period  anterior  to  the  deposition  of 
tlie  Cambrian  sediments,  and  will  correspond  with  the  newer 
gneissic  series  of  our  Appalachian  region.  There  exists,  in  the 
Highlands  of  Scotland,  a  great  volume  of  fine-grained,  thin-bed- 
ded mica-schists  with  andalusite,  staurolite,  and  cyanite,  which 
are  met  with  in  Argyleshire,  Aberdeenshire,  Banffshire,  and  the 
Shetland  Isles.  Rocks  regarded  by  Harkness  as  identical  with 
these  of  the  Scottish  Highlands  also  occur  in  Donegal  and 
Mayo  in  Ireland.  Through  the  kindness  of  the  Rev.  Professor 
Haughton  of  Trinity  College,  and  Mr.  Robert  H.  Scott,  then 
of  Dublin,  I  received  some  years  since  a  large  collection  of 
the  crystalline  rocks  of  Donegal,  which  I  am  thus  enabled  to 
compare  with  those  of  North  America,  and  to  assert  the  exist- 
ence, in  the  northwest  of  Ireland,  of  our  second  and  third 
series  of  crystalline  schists.  The  Green  Mountain  rocks  are 
there  exactly  represented  by  the  dark-colored  chromiferous 
serpentines  of  Aghadoey,  and  the  steatite,  crystalline  talc,  and 
actinolite  of  Crohy  Head  ;  while  the  mica-schist  of  Loch  Derg, 
with  white  quartz,  blue  cyanite,  staurolite,  and  garnet,  all 
united  in  the  same  fragment,  cannot  be  distinguished  from 
specimens  found  at  Cavendish,  Vermont,  and  Windham,  Maine. 
The  fine  grained  andalusite-schists  of  Clooney  Lough  are  ex- 
actly like  those  from  Mount  Washington  ;  while  the  granitoid 
mica-slates  from  several  other  localities  in  Donegal  are  not  less 
clearly  of  the  type  of  the  White  Mountain  series.  Similar 
micaceous  schists,  with  andalusite  (chiastolite),  occur  on  Skid- 
daw,  in  Cumberland,  England,  the  relations  of  which  have 

*  Paleontology  of  New  York,  Vol.'  III.,  Introduction,  page  93. 


XIII.J  GEOGNOSY  OF  THE  APPALACHIANS.  273 

been  clearly  defined  by  Sedgwick,  who  groups  the  rocks  of 
Skiddaw  into  four  divisions.  The  lowest  of  these,  succeeding 
the  granite,  is  a  series  of  crystalline  rocks,  not  described  litho- 
logically,  with  mineral  veins,  "  having  some  resemblance  to  the 
rocks  of  Cornwall,"  and  including,  towards  the  summit,  "  chi- 
astolite-schists  and  chiastolite-rocks."  These  are  followed  in 
ascending  order  by  two  great  series  of  slates  and  grits,  suc- 
ceeded by  a  fourth  division  of  schists,  sometimes  carbonaceous, 
holding  in  parts  fucoids  and  graptolites,  which  are  apparently 
overlaid  discordantly  by  sundry  trappean  conglomerates  and 
chloritic  slates.*  The  graptolites  of  the  Skiddaw  slates  are 
found  to  be  identical  with  those  of  the  Levis  formation,t  and 
it  is  worthy  of  notice  that  although  Sedgwick  places  the  mica- 
schists  with  andalusite  (chiastolite)  so  far  below  the  graptolitic 
beds,  he  elsewhere,  in  comparing  the  rocks  of  North  Wales 
and  Cumberland,  states  that  the  chloritic  and  micaceous  rocks 
of  Anglesea  and  Caernarvon  are  not  represented  in  Cumber: 
land,  being  distinct  from  the  other  rocks  of  North  Wales,  and 
much  older.  { 

In  Victoria,  Australia,  the  position  of  the  chiastolite  schists, 
according  to  Selwyn,  is  beneath  the  graptolitic  slates.  Boblaye, 
it  is  true,  asserted  in  1838  that  the  chiastolite-schists  of  Les 
Salles,  near  Pontivy  in  Brittany,  include  Orthis  and  Calymene;  § 
but  when  we  remember  that  even  experienced  observers  in  the 
White  Mountains  for  a  time  mistook  for  remains  of  Crustacea 
and  brachiopods,  certain  obscure  forms,  which  they  afterwards 
found  not  to  be  organic,  and  that  Dana,  in  this  connection,  has 
called  attention  to  the  deceptive  resemblance  to  fossils  presented 
by  some  imperfectly  developed  chiastolite  crystals  in  the  same 
region,||  we  may  well  require  a  verification  of  Boblaye's  obser- 
vation, especially  since  we  find  that  more  recently  D'Archiac 
and  Dalimier  agree  with  De  Beaumont  and  Dufrenoy  in  placing 

*  Synopsis  of  British  Palaeozoic  Rocks,  p.  Ixxxiv,  being  an  Introduction  to 
McCoy's  Brit.  Pal.  Fossils  (1855). 

t  Harkness  and  Salter,  Quar.  Jour.  Geol.  Soc.,  XIX.  135. 
+  Geol.  Journal  (1845),  IV.  583. 
§  Bull.  Soc.  Geol.  de  Fr.,  X.  227. 
||  American  Journal  of  Science  (2),  I.  415,  V.  116. 

12*  B 


274  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

the  chiastolite-schists  of  Brittany  at  the  very  base  of  the  tran- 
sition sediments,  marking  the  summit  of  the  crystalline  schists.* 

With  regard  to  the  crystalline  schists  of  Lakes  Huron  and 
Superior,  to  which  the  name  of  the  Huronian  system  has  been 
given,  the  observations  of  all  who  have  studied  the  region 
concur  in  placing  them  unconformably  beneath  the  sediments 
which  are  supposed  to  represent  the  base  of  the  New  York 
system ;  while,  on  the  other  hand,  they  rest  unconformably  on 
the  Laurentian  gneiss,  fragments  of  which  are  included  in  the 
Huronian  conglomerates.  The  gneissic  series  of  the  Green 
Mountains  had,  however,  as  we  have  seen,  been,  since  1841, 
regarded,  by  the  brothers  Rogers,  Mather,  Hall,  Hitchcock, 
Adams,  Logan,  myself,  and  others,  as  Lower  Silurian  (Cam- 
brian of  Sedgwick).  Eaton  and  Emmons  had  alone  claimed 
for  it  a  pre-Cambrian  age,  until,  in  1862,  Macfarlane  ventured 
to  unite  it  with  the  Huronian  system,  and  to  identify  both  with 
the  crystalline  schists  of  a  similar  age  in  Norway.  Later  ob- 
servations in  Michigan  justify  still  further  this  comparison;  for 
not  only  the  more  schistose  beds  of  the  Green  Mountain  series, 
but  even  the  mica-schists  of  the  third  or  White  Mountain 
series,  with  staurolite  and  garnet,  are  represented  in  Michigan, 
as  appears  by  the  recent  collections  of  Major  Brooks  of  the 
Geological  Survey  of  Michigan,  kindly  placed  in  my  hands  for 
examination.  He  informs  me  that  these  latter  schists  are  the 
highest  of  the  crystalline  strata  in  the  northern  peninsula. 
(Ante,  page  18.) 

To  the  north  of  Lake  Superior,  as  I  have  already  shown 
elsewhere,  the  schists  of  this  third  series,  which,  as  early  as 
1861,  I  compared  to  those  of  the  Appalachians,  are  widely 
spread  ;  while  in  Hastings  County,  forty  miles  north  of  Lake 
Ontario,  rocks  having  the  mineralogical  and  lithological  charac- 
ters both  of  the  second  and  third  series  are  found  resting  011 
the  first  or  Laurentian  series,  the  three  apparently  unconform- 
able,  and  all  in  turn  overlaid  by  horizontal  Trenton  limestone,  t 

We  have  shown,  that  in  Pennsylvania,  while  some  of  these 

»  Bull.  Soc.  Geol.  de  Fr.  (2),  XVIII.  664. 

t  American  Journal  of  Science  (2),  XXXI.  395,  and  L.  85. 


XIII.]  GEOGNOSY   OF   THE   APPALACHIANS.  275 

schists  of  the  second  and  third  series  were  regarded  as  altered 
primal  rocks  by  H.  D.  Rogers,  §others,  lithologically  similar, 
were  referred  by  him  to  the  older  so-called  azoic  series,  which 
we  believe  to  be  their  true  position.  Professor  W.  B.  Rogers 
has  lately  informed  me  that  in  Virginia  a  gneissic  series,  having 
the  characters  of  the  Green  Mountain  rocks,  is  clearly  overlaid 
unconformably  by  the  lowest  primal  palaeozoic  strata  of  the 
region.  Coming  northward,  the  uncrystalline  argillites  and 
sandstones  holding  Paradoxides,  at  Braintree,  Massachusetts,* 
and  St.  John,  New  Brunswick,  overlie  unconformably  crystal- 
line schists  of  the  second  series ;  and  in  the  latter  region,  in 
one  locality,  rocks  which  are  by  Bailey  and  Matthew  regarded 
of  Laurentian  age.  In  Newfoundland,  in  like  manner,  a  great 
series  of  crystalline  schists,  in  which  Mr.  Murray  recognizes  the 
Huronian.  system  as  first  studied  and  described  by  him  in  the 
West,  is  unconformably  overlaid  by  a  group  of  sandstones,  lime- 
stones, and  slates,  holding  Paradoxides.  The  peculiar  gneisses 
and  mica-schists  of  the  White  Mountain  series  appear  to  be 
developed  to  a  great  extent  in  Newfoundland,  which  led  me  to 
propose  for  them  the  name  of  the  Terranovan  system. t 

From  the  part  which  the  ruins  of  these  rocks  play  in  the 
production  of  succeeding  sediments,  it  is  not  always  easy  to 
define  the  limits  between  the  ancient  mica-schists  and  the 
Cambrian  strata  in  these  northeastern  regions.  It  is  not  im- 
possible that  the  two  may  graduate  into  each  other,  as  some 
have  supposed,  in  Newfoundland  and  Nova  Scotia ;  but  until 
further  light  is  thrown  upon  the  subject,  I  am  disposed  to  re- 
gard the  relation  between  the  two  as  one  of  derivation  rather 
than  of  passage. 

We  have  already  alluded  to  the  history  of  the  rocks  of  the 
White  Mountains,  formerly  looked  upon  as  primary,  and  by 
Jackson  described  as  an  old  granitic  and  gneissic  axis  uplifting 
the  more  recent  Green  Mountain  rocks.  .  Their  manifest  differ- 
ences from  the  more  ancient  gneiss  of  the  Adirondacks,  and 
their  apparent  superposition  to  the  Green  Mountain  series,  then 

*  Hunt,  Proc.  Boat.  Soc.  Nat.  Hist.,  October  19,  1870. 
f  American  Journal  of  Science  (2),  L.  87. 


276  GEOGNOSY   OF  THE  APPALACHIANS.  [XIII. 

regarded  by  the  Messrs.  Eogers  as  belonging  to  the  Champlain 
division,  led  them,  in  1846,  to  look  upon  the  White  Mountains 
as  altered  strata  belonging  to  the  Levant  division  of  their 
classification,  corresponding  to  the  Oneida,  Medina,  and  Clinton 
of  the  New  York  system.  In  1848,  Sir  William  Logan  came 
to  a  somewhat  similar  conclusion.  Accepting,  as  we  have  seen, 
the  view  of  Ernrnons,  that  the  strata  about  Quebec  included  a 
portion  of  the  Levant  division,  and  regarding  the  Green  Moun- 
tain gneisses  as  the  equivalents  of  these,  he  was  induced  to 
place  the  White  Mountain  rocks  still  higher  in  the  geological 
series  than  the  Messrs.  Rogers  had  done,  and  expressed  his 
belief  that  they  might  be  the  altered  representatives  of  the 
New  York  system,  from  the  base  of  the  Lower  Helderberg  to  the 
top  of  the  Chemung ;  in  other  words,  that  they  were  not 
Middle  Silurian,  but  Upper  Silurian  and  Devonian.  This  view, 
adopted  and  enforced  by  me,*  was  further  supported 'by  Lesley 
in  1860,  and  has  been  generally  accepted  up  to  this  time.  In 
1870,  however,  I  ventured  to  question  it,  and  in  a  published 
letter,  addressed  to  Professor  Dana,  concluded,  from  a  great 
number  of  facts,  that  there  exists  a  system  of  crystalline  schists 
distinct  from,  and  newer  than,  the  Laurentian  and  Huronian, 
to  which  I  gave  the  provisional  name  of  Terranovan  [since 
called  Montalban],  constituting  the  third  or  White  Mountain 
series,  which  appears  not  only  throughout  the  Appalachians,  but 
westward  to  the  north  of  Lake  Ontario,  and  around  and  beyond 
Lake  Superior,  f  Although  I  have,  in  common  with  most  other 
American  geologists,  maintained  that  the  crystalline  rocks  of 
the  Green  Mountain  and  White  Mountain  series  are  altered 
palaeozoic  sediments,  I  find,  on  a  careful  examination  of  the 
evidence,  no  satisfactory  proof  of  such  an  age  and  origin,  but 
an  array  of  facts  which  appear  to  me  incompatible  with  the 
hitherto  received  view,  and  lead  me  to  conclude  that  the  whole 
of  our  crystalline  schists  of  eastern  North  America  are  not  only 
pre-Silurian  but  pre-Cambrian  in  age. 

*  Geological  Survey  of  Canada,  Report  1847  -  48,  p.  58  ;   also  American 
Journal  of  Science  (2),  IX.  19. 

t  American  Journal  of  Science  (2),  L.  83. 


XIII.]  GEOGNOSY  OF  THE  APPALACHIANS.  277 

In  what  precedes  I  have  endeavored  to  discuss  briefly  and 
impartially  some  of  the  points  in  the  history  of  the  older  rocks, 
and  of  the  views  which  during  the  past  thirty  years  have  heen 
entertained  as  to  their  age  and  geological  relations,  both  in 
America  and  in  Europe.  I  have  said  some  things  which  will 
provoke  criticism,  and  at  the  same  time,  I  trust,  lead  to  further 
study  of  these  rocks,  a  correct  knowledge  of  which  lies  at  the 
basis  of  geological  science. 

I  cannot,  however,  conclude  this  part  of  my  subject  without 
referring  to  the  views  put  forth  in  1869  by  Professor  Hermann 
Credner,  of  Leipzig,  in  an  essay  on  the  Eozoic  or  pre-Silurian 
formations  of  ^orth  America.*  With  Macfarlane,  he  refers  to 
the  Huronian  the  gneissic  series  of  the  Green  Mountains,  but 
includes  with  it,  as  part  of  the  Huronian  system,  the  so-called 
Lower  Taconic  rocks  of  Vermont,  "with  remains  of  annelids  and 
crinoids."  Credner  thus  falls  into  the  very  error  against  which 
Emmons  warned  American  geologists,  namely,  the  confounding 
in  one  system  the  ancient  crystalline  schists  with  the  newer 
fossiliferous  sediments.  Resting  unconformably  on  these,  he 
places,  first,  the  Upper  Taconic,  corresponding,  according  to 
him,  to  a  part  of  the  Quebec  group ;  and,  second,  the  Potsdam 
sandstone.  In  this  he  has  copied,  for  the  most  part,  Marcou, 
who,  however,  groups  the  whole  of  these  various  divisions  in 
the  Taconic  system ;  while  Credner,  rejecting  the  name,  unites 
a  portion  of  the  Taconic  of  Emmons  with  the  Huronian  system, 
and  refers  the  other  portion,  together  with  the  Potsdam,  to  the 
Silurian.  These  same  views  are  set  forth  in  a  more  recent 
paper,  by  the  same  author,  on  the  Alleghany  system,  which  is 
accompanied  with  sections  and  a  geologically  colored  map.t 
In  this,  not  content  with  including  in  the  Huronian  both  the 
fossiliferous  strata  of  the  Levis  formation  and  the  crystalline 
schists  of  the  Green  Mountains,  he  refers  the  gneisses  and  mica- 
schists  of  the  White  Mountains  to  the  same  system  ;  while  the 
broad  area  of  similar  rocks  from  their  base  to  the  sea  at  Port- 

*  Die  Gliederung  der  Eozoischen  Formationsgruppe,  u.  s.  w.,  p.  63.    Halle, 
1869. 
t  Petermann's  Geographische  Mittheilungen.     2  Heft,  1871. 


278  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

land  is  regarded  as  Laurentian.  This,  on  Credner's  map,  is 
also  made  to  include,  with  the  exception  of  the  White  Moun- 
tains themselves,  all  the  rocks  of  the  third  or  White  Moun- 
tain series,  which  cover  so  large  a  part  of  New  England.  Those 
who  have  followed  the  historical  sketch  already  given  can  see 
how  widely  these  notions  of  Credner  diifer  from  those  of  Em- 
mons,  and  from  all  other  American  geologists,  and  how  much 
they  are  at  variance  with  the  present  state  of  our  knowledge. 
It  is  much  to  be  regretted  that  so  good  a  geologist  and  litholo- 
gist  should,  from  a  too  superficial  study,  have  fallen  into  these 
errors,  which  can  only  retard  the  progress  of  comparative  ge- 
ognosy, for  which  he  has  done  so  much.  In  England,  again, 
Credner  confounds  the  Cambrian  and  Huronian,  referring  to 
the  latter  system  the  whole  of  the  Longmynd  rocks  with  their 
characteristic  Cambrian  fauna,  —  a  view  which  is  supported  only 
by  the  conjectured  Cambrian  age  of  the  crystalline  schists  of 
Anglesea,  which  are  pre-Cambrian  and  probably  Huronian,  like 
the  Urschiefer  of  Scandinavia,  which  Credner  correctly  refers 
to  the  latter  system,  as  Macfarlane  and  Bigsby  had  done  before 
him.  He,  moreover,  recognizes  in  the  similar  crystalline  schists 
of  Scotland,  the  Urals,  and  various  parts  of  Germany,  includ- 
ing those  of  Bavaria  and  Bohemia,  a  newer  system,  overlying 
the  primary  or  Laurentian  gneiss,  and  corresponding  to  the 
Huronian  or  Green  Mountain  series  of  North  America ;  while 
he  suggests  a  correspondence  with  similar  rocks  in  Japan,  Ben- 
gal, and  Brazil.  In  a  collection  of  rocks  brought  from  the 
latter  country  by  Professor  C.  F.  Hartt,  I  have  found,  as  else- 
where stated,*  what  appear  to  be  representatives  of  the  three 
types  of  crystalline  schists  which  have  been  distinguished  in 
eastern  North  America. 

[I  have  not  in  the  preceding  discussion  alluded  to  the  Norian 
series,  otherwise  called  the  Labradorian  or  Upper  Laurentian, 
for  the  reason  that  although  largely  developed  in  the  southern 
part  of  the  Adirondack  region,  it  does  not  occur  on  our  line  of 
section,  and,  moreover,  was  not  certainly  known  in  the  Appala- 
chians. Subsequent  observations  of  the  Geological  Survey  of 

*  The  Nation,  December  1,  1870 ;  and  Hartt's  Geology  of  Brazil,  p.  550. 


XIII.]  GEOGNOSY  OF  THE  APPALACHIANS.  279 

New  Hampshire  having,  however,  shown  the  existence  of  rocks 
supposed  to  belong  to  this  series  in  the  region  of  the  White 
Mountains,  a  brief  history  of  it  will  not  be  out  of  place ;  while 
for  further  details  the  student  is  referred  to  a  paper  by  the  present 
writer  in  the  American  Journal  of  Science  for  February,  1870 
((2)  XLIX.  180).  The  rocks  of  this  series  were  recognized  by 
Emmons  in  Essex  County,  New  York,  and  described  by  him  in 
1842,  in  the  geology  of  the  Northern  District  of  that  State 
(page  27).  They  were  by  him  correctly  regarded  as  identical 
with  the  hypersthene  rock  of  the  Western  Islands  of  Scotland, 
described  by  MacCulloch,  and  were  looked  upon  as  intru- 
sive. Similar  rocks  in  erratic  masses  abound  in  the  valley  of 
the  St.  Lawrence,  but  were  first  found  in  place  by  Logan,  and 
described  by  me  in  the  Keport  of  the  Geological  Survey  of 
Canada  for  1852  (page  167).  They  were  shown  by  Logan  to  be- 
long to  a  great  stratified  series,  which  was  at  first  included  by  him 
in  the  Laurentian.  Subsequent  investigation,  however,  showed 
that  these  rocks  rest  unconformably  on  the  Laureutian  gneiss, 
and  he  therefore  called  them  Upper  Laurentian.  Inasmuch  as 
they  are  largely  displayed  in  Labrador,  and  moreover  consist  in 
great  part  of  labradorite  feldspar,  the  name  of  the  Labradorian 
series  was  also  given  to  them.  In  1870  it  was  shown  by  me,  in 
the  paper  above  referred  to,  that  these  rocks  were  apparently 
identical  with  the  norites  of  Esmark,  found  in  Norway  under 
conditions  very  like  those  of  the  Labradorian  rocks  of  North 
America,  and  that  this  name  of  norite,  given  in  allusion  to 
that  country,  has  the  right  of  priority.  I  therefore  propose  to 
speak  of  them  by  that  name,  and  moreover  to  designate  as  the 
Norian  series  the  great  formation  of  crystalline  stratified  rocks 
of  which  the  norites  make  up  so  large  a  part.  The  typical 
norites  consist  chiefly  of  a  triclinic  feldspar,  varying  in  com- 
position from  anorthite  to  andesine,  but  generally  near  labra- 
dorite in  composition.  The  color  of  these  rocks  is  ordinarily 
some  shade  of  blue,  —  from  bluish-black  or  violet  to  bluish- 
gray,  smoke-gray,  or  lavender,  more  rarely  passing  into  flesh- 
red,  and  occasionally  greenish-blue,  greenish  or  bluish  white. 
The  weathered  surfaces  are  opaque  white.  These  norites  are 


280  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

sometimes  nearly  pure  feldspar,  but  often  include  small  portions 
of  hypersthene,  pyroxene,  or  hornblende,  —  the  former  two 
being  sometimes  associated  in  the  same  specimen,  and  in  con- 
tact with  each  other.  A  black  mica  (biotite),  red  garnet,  epi- 
dote,  chrysolite,  and  menacannite  (titanic  iron)  are  frequently 
present  in  these  rocks  ;  quartz,  however,  is  rarely  seen,  and  then 
only  in  small  quantities.  Through  an  admixture  of  the  first- 
named  minerals  these  norites  pass  into  hyperite,  diabase,  and 
diorite.  The  norites  vary  in  texture,  being  sometimes  coarsely 
granitoid,  and  at  other  times  fine  grained  and  nearly  impalpable. 
The  coarser  varieties  often  present  large  cleavable  masses,  show- 
ing the  striae  characteristic  of  the  polysynthetic  macles  of  the 
triclinic  feldspars,  and  sometimes  exhibit  a  fine  play  of  colors, 
as  in  the  well-known  specimens  from  Labrador.  A  gneissic 
structure  is  well  marked  in  many  of  the  less  coarse-grained 
varieties  of  norite,  and  the  lines  of  bedding  are  shown  by  the 
arrangement  of  the  various  foreign  minerals.  Although  norites 
predominate  in  the  Norian  series,  they  are  found  in  the  area 
of  these  rocks  which  is  seen  to  the  north  of  Montreal  to  be  in- 
terstratified  with  beds  of  micaceous  orthoclase-gneiss,  quartzite, 
and  crystalline  limestone,  not  unlike  those  met  with  in  the 
Laurentian  and  White  Mountain  series.  It  was  from  their  dis- 
tribution in  this  region  that  Sir  William  Logan  was  enabled  to 
show  that  the  rocks  of  the  Norian  series  rest  uncoiiformably 
upon  the  gneisses  and  limestones  of  the  Laurentian.  Further 
evidence  of  the  same  kind  was  obtained  -by  Mr.  Eichardson,  in 
1869,  on  the  north  side  of  the  Gulf  of  St.  Lawrence,  where 
rocks  of  the  Norian  series  were  found  to  lie  in  discordant 
stratification,  and  at  moderate  angles  on  the  nearly  vertical 
Laurentian  gneiss.  The  norites  may  be  readily  studied  in 
Essex  County,  New  York,  where  they  reach  the  shore  of  Lake 
Champlain  just  above  the  town  of  Westport,  and  include  the 
great  deposits  of  titanic  iron  ores  of  this  region.  The  titanic 
ores  of  Bay  St.  Paul,  Lake  St.  John,  and  the  Bay  of  Seven 
Islands,  in  Canada,  also  occur  in  Norian  rocks.  In  all  of  these 
localities  they  appear  to  be  directly  superposed  on  the  Lauren- 
tian ;  but  in  the  vicinity  of  St.  John,  New  Brunswick,  a  small 


XIIL]  GEOGNOSY  OF  THE  APPALACHIANS.  281 

area  of  noriteg  is  found  to  occupy  a  position  in  contact  with 
rocks  regarded  as  belonging  to  the  Huronian  and  the  White 
Mountain  series.  The  rocks  which  are  referred  to  the  Norian 
series  in  the  White  Mountain  region,  according  to  Hitchcock, 
rest  upon  the  gneisses  and  mica-schists  of  the  White  Moun- 
tains ;  while  these  overlie  unconformably  a  more  ancient  series 
of  granitoid  gneiss,  supposed  to  represent  the  Laurentian. 

The  hypersthene  rock  of  Skye  was  by  MacCulloch  regarded 
as  an  eruptive  rock ;  and  Giekie,  in  his  memoir  on  the  geology 
of  a  part  of  Skye,  published  in  1858  (Quarterly  Journal  of  the 
Geological  Society,  XIV.  page  1),  appears  to  include  them  with 
certain  syenites  and  greenstones,  which  he  vaguely  speaks  of  as 
not  intrusive,  though  eruptive  after  the  manner  of  granites 
(loc.  cit.,  pp.  11-14).  Specimens  of  these  rocks  from  Loch 
Scavig,  and  others  in  MacCulloch's  collection  from  that  vicinity, 
which  I  have  examined,  are,  however,  identical  with  the  North 
American  norites,  whose  stratified  character  is  undoubted.  I 
called  attention  to  these  resemblances  in  the  Dublin  Quarterly 
Journal  for  July,  1863  (ante,  page  33);  and  Professor  Haugh- 
ton,  of  Dublin,  who  in  1864  visited  Loch  Scavig,  subsequently 
described  and  analyzed  the  norite  from  that  locality  ;  which 
is,  according  to  him,  evidently  "  a  bedded  metamorphic  rock." 
(Dublin  Quarterly  Journal  for  1865,  page  94.) 

The  distribution  of  the  crystalline  rocks  of  the  Norian, 
Huronian,  and  Montalban  or  White  Mountain  series  would 
seem  to  show  that  these  are  remaining  portions  of  great,  dis- 
tinct, and  unconformable  series,  once  widely  spread  out  over  a 
more  ancient  floor  of  granitic  gneiss  of  Laurentian  age ;  but 
that  the  four  series  thus  indicated  include  the  whole  of  the 
crystalline  stratified  rocks  of  New  England  is  by  no  means 
certain.  How  many  more  such  formations  may  have  been  laid 
down  over  this  region,  and  subsequently  swept  away,  leaving 
no  traces,  or  only  isolated  fragments,  we  may  never  know  ;  but 
it  is  probable  that  a  careful  study  of  the  geology  of  New  Eng- 
land and  the  adjacent  British  Provinces  may  establish  the  ex- 
istence of  many  more  than  the  four  series  above  enumerated. 
When  it  is  considered  that  we  find  within  the  limits  of  southern 


282  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

New  Brunswick  alone  small  areas  of  palaeozoic  sediments  which 
are  shown  by  their  organic  remains  to  belong  to  not  less  than 
five  periods,  namely,  Menevian,  Lower  Helderberg,  Chemung, 
Lower  Carboniferous,  and  Carboniferous,  all  perfectly  well  dis- 
tinguished, and  each  reposing  directly  upon  the  ancient  crys- 
talline rocks,  we  are  prepared  for  a  history  not  less  varied  and 
complex  for  the  rocks  belonging  to  Eozoic  time.  (See  the 
author's  Address  before  the  American  Institute  of  Mining  En- 
gineers, in  their  Proceedings  for  February,  1873.) 

Professor  C.  H.  Hitchcock,  from  the  results  of  the  Geological 
Survey  of  New  Hampshire,  now  in  progress,  announces,  in  1873 
and  1874,  a  large  number  of  divisions  in  the  crystalline  rocks 
of  this  State.  The  Norian  series  there,  according  to  him,  rests 
unconformably  upon  ancient  gneisses,  which,  as  he  suggests,  be- 
long perhaps  to  the  Laureritian,  the  appearance  of  which  in  north- 
eastern Massachusetts  I  pointed  out  in  1870.  With  the  Norian 
he  has  however  included  a  great  series  of  granites  and  of  compact 
felsites,  some  of  which,  from  specimens,  appear  identical  with  the 
orthophyres  of  our  eastern  coasts,  of  Lake  Superior,  and  Missouri. 
These,  so  far  as  my  observations  go,  are  in  no  way  related  to  the 
Norian,  but  probably  belong  to  the  Huronian  series.  (Ante,  page 
187.)  Besides  these,  he  recognizes  the  White  Mountain  series 
of  gneisses  and  andalusite-schists  (Montalban).  He  describes, 
under  the  name  of  gneiss,  the  so-called  granites  of  Concord 
and  Fitzwilliam,  which  I  had  already,  in  1870,  declared  to  be 
gneisses  associated  with  the  mica-schists  of  the  Montalban 
series.  (Ante,  page  188.)  This  series  he  supposes  to  be  more 
ancient  than  the  well-characterized  Huronian  rocks  of  the  State  ; 
but  admits  in  addition  a  second  and  more  recent  series  of  mica- 
schists  with  andalusite  and  staurolite,  named  the  Coos  group. 
Further  researches  in  this  disturbed  region  will  be  required  to 
determine  whether,  besides  this  series  of  andalusite  and  stau- 
rolite-bearing  mica-schists,  which  (associated  with  gneisses) 
occurs  in  other  regions,  as  I  have  in  the  previous  pages  of  this 
essay  endeavored  to  show,  above  the  Huronian,  there  is  another 
and  an  older  series  of  similar  rocks,  or  whether  the  two  are  one 
and  the  same  series,  repeated  by  stratigraphical  accidents.] 


XIII.]  ORIGIN   OF   CRYSTALLINE   ROCKS.  283 

II.     THE  ORIGIN  OF  CRYSTALLINE   ROCKS. 

We  now  approach  the  second  part  of  our  subject,  namely, 
the  genesis  of  the  crystalline  schists  whose  history  we  have 
just  discussed.  The  origin  of  the  mineral  silicates  which  make 
up  a  great  portion  of  the  crystalline  rocks  of  the  earth's  sur- 
face is  a  question  of  much  geological  interest,  which  has  been 
to  a  great  degree  overlooked.  The  gneisses,  mica-schists,  and 
argillites  of  various  geological  periods  do  not  differ  very  greatly 
in  chemical  constitution  from  modern  mechanical  sediments, 
and  are  now,  by  the  greater  number  of  geologists,  regarded  as 
resulting  from  a  molecular  rearrangement  of  similar  sediments 
formed  in  earlier  times  by  the  disintegration  of  previously  ex- 
isting rocks,  not  very  unlike  them  in  composition  ;  the  oldest 
known  formations  being  still  composed  of  crystalline  stratified 
deposits  presumed  to  be  of  sedimentary  origin.  Before  these 
the  imagination  conceives  yet  earlier  rocks,  until  we  reach  the 
surface  of  unstratified  material  which  the  globe  may  be  supposed 
to  have  presented  before  water  had  begun  its  work.  It  is  not, 
however,  my  present  plan  to  consider  this  far-off  beginning  of 
sedimentary  rocks,  which  I  have  elsewhere  discussed.  (Ante, 
page  63.) 

Apart  from  the  rocks  just  referred  to,  whose  composition  may 
be  said  to  be  essentially  quartz  and  aluminous  silicates,  chiefly 
in  the  forms  of  feldspars  and  micas,  there  is  another  class  of 
crystalline  silicated  rocks,  which,  though  far  less  important  in 
bulk  than  the  last,  is  of  great  and  varied  interest  to  the  litholo- 
gist,  the  mineralogist,  the  geologist,  and  the  chemist.  The  rocks 
of  this  second  class  may  be  defined  as  consisting  in  great  part 
of  the  silicates  of  the  protoxide  bases,  lime,  magnesia,  and  fer- 
rous oxide,  either  alone,  or  in  combination  with  silicates  of 
alumina  and  alkalies.  They  include  the  following  as  their 
chief  constituent  mineral  species  :  pyroxene,  hornblende,  chrys- 
olite, serpentine,  talc,  chlorite,  epidote,  garnet,  and  triclinic 
feldspars,  such  as  labradorite.  The  great  types  of  this  second 
class  are  not  less  well  defined  than  the  first,  and  consist  of  py- 
roxenic  and  hornblendic  rocks,  passing  into  diorites,  diabases, 


284  ORIGIN   OF  CRYSTALLINE   ROCKS.  [XIII. 

ophiolites,  and  talcose,  chloritic,  and  epidotic  rocks.  Inter- 
mediate varieties  resulting  from  the  association  of  the  minerals 
of  this  class  with  those  of  the  first,  and  also  with  the  materials 
of  non-silicated  rocks,  such  as  limestones  and  dolomites,  show 
an  occasional  blending  of  the  conditions  under  which  these 
various  types  of  rocks  were  formed. 

The  distinctions  just  drawn  between  the  two  great  divisions 
of  silicated  rocks  are  not  confined  to  stratified  deposits,  but 
are  equally  well  marked  in  eruptive  and  unstratified  masses, 
among  which  the  first  type  is  represented  by  trachytes  and 
granites ;  and  the  second,  by  dolerites  and  diorites.  This  fun- 
damental difference  between  acidic  and  basic  rocks,  as  the  two 
classes  have  been  called,  finds  its  expression  in  the  theories  of 
Phillips,  Durocher,  and  Bunsen,  who  have  deduced  all  silicated 
rocks  from  two  supposed  layers  of  molten  matter  within  the 
earth's  crust,  consisting  respectively  of  acidic  and  basic  mix- 
tures ;  the  tiachytic  and  pyroxenic  magmas  of  Bunsen.  From 
these,  by  a  process  of  partial  crystallization  and  eliquation,  or 
by  commingling  in  various  proportions,  those  eruptive  rocks 
which  depart  more  or  less  from  the  normal  types  are  supposed 
by  the  theorists  of  this  school  to  be  generated.  (Ante,  pages 
3  and  23.)  The  doctrine  that  these  eruptive  rocks  are  not 
derived  directly  from  a  hitherto  uncongealed  nucleus,  but  are 
softened  and  crystallized  sediments,  in  fact,  that  the  whole  of 
the  rocks  at  present  known  to  us  have  at  one  time  been 
aqueous  deposits,  has,  however,  found  its  advocates.  In  sup- 
port of  this  view,  I  have  endeavored  to  show  that  the  natural 
result  of  forces  constantly  in  operation  tends  to  resolve  me- 
chanical sediments  into  two  classes  :  the  one  coarse,  sandy,  and 
permeable  ;  the  other  fine,  clayey,  and  impervious.  The  action 
of  infiltrating  atmospheric  waters  on  the  first  and  more  sili- 
cious  strata  will  remove  from  them  lime,  magnesia,  iron-oxide, 
and  soda,  leaving  behind  silica,  alumina,  and  potash,  —  the 
elements  of  granitic,  gneissic,  and  trachytic  rocks.  The  finer 
and  more  aluminous  sediments  (including  the  ruins  of  the  soft 
and  easily  abraded  silicates  of  the  pyroxene  group),  resisting 
the  penetration  of  the  water,  will,  on  the  contrary,  retain  their 


XIIL]  ORIGIN   OF  CRYSTALLINE  ROCKS.  285 

alkalies,  lime,  magnesia,  and  iron,  and  thus  will  have  the  com- 
position of  the  more  basic  rocks.  [We  find,  in  fact,  in  the 
sediments  of  various  geological  periods,  not  only  beds  of  clay 
and  marl  corresponding  to  the  second  class,  but  strata  made 
up  in  great  part  of  mechanically  disintegrated  though  chemi- 
cally unchanged  orthoclase,  with  quartz,  the  debris  of  granitic 
rocks,  constituting  what  is  called  arkose.  Beds  of  this  kind, 
as  will  be  seen  in  the  following  paper  on  the  Geology  of  the 
Alps,  have  even  been  mistaken  for  granite  and  gneiss,  and 
similar  recomposed  rocks  occur  in  the  mesozoic  sandstones  of 
New  England  and  New  Jersey.  Such  processes  of  disintegra- 
tion and  decay  have  probably  been  going  on  from  very  re- 
mote times,  and  the  crystalline  rearrangement  of  the  resulting 
rocks  may  be  supposed  to  give  rise  to  true  crystalline  schists, 
or  their  aqueo-igneous  fusion  to  eruptive  rocks.  (Ante,  pages 
14  and  23.)] 

A  little  consideration  will,  however,  show  that  this  process 
is  inadequate  to  explain  the  production  of  many  of  the  vari- 
eties of  crystalline  silicated  rocks.  Such  are  serpentine,  steatite, 
chrysolite,  hornblende,  diallage,  chlorite,  pinite,  labradorite, 
and  orthoclase,  all  of  which  mineral  species  form  rock-masses 
by  themselves,  frequently  almost  without  admixture.  No 
geological  student  will  now  question  that  all  of  these  rocks 
occur  as  members  of  stratified  formations.  Moreover,  the  man- 
ner in  which  serpentines  are  found  interstratified  with  steatite, 
chlorite,  argillite,  diorite,  hornblende,  and  feldspar  rocks,  and 
these,  in  their  turn,  with  quartzites  and  orthoclase  rocks,  is 
such  as  to  forbid  the  notion  that  all  of  these  various  materials 
have  been  deposited,  with  their  present  composition,  as  me- 
chanical sediments  from  the  ruins  of  pre-existing  rocks  of  plu- 
tonic  origin. 

There  are  two  hypotheses  which  have  been  proposed  to  ex- 
plain the  origin  of  these  various  silicated  rocks,  and  especially 
of  the  less  abundant,  and,  as  it  were,  exceptional  species  just 
mentioned.  The  first  of  these  supposes  that  the  minerals  of 
which  they  are  composed  have  resulted  from  an  alteration  of 
previously  existing  minerals  of  plutonic  rocks,  often  very  unlike 


286  ORIGIN   OF  CRYSTALLINE  ROCKS.  [XIII. 

in  composition  to  the  present,  by  the  taking  away  of  certain 
elements  and  the  addition  of  certain  others.  This  is  the 
theory  of  metamorphism  by  pseudomorphic  changes,  as  they 
are  called,  and  is  the  one  taught  by  the  now  reigning  school  of 
chemical  geologists,  of  which  the  learned  and  laborious  Bischof, 
whose  recent  death  science  deplores,  may  be  regarded  as  the 
great  exponent.  The  second  hypothesis  supposes  that  the 
elements  of  these  various  rocks  were  originally  deposited  as, 
for  the  most  part,  chemically  formed  sediments,  or  precipitates ; 
and  that  the  subsequent  changes  have  been  simply  molecular, 
or,  at  most,  confined  in  certain  cases  to  reactions  between  the 
mingled  elements  of  the  sediments,  with  the  elimination  of 
water  and  carbonic  acid.  It  is  proposed  to  consider  briefly 
these  two  opposite  theories,  which  seek  to  explain  the  origin 
of  the  rocks  in  question  respectively  by  pseudomorphic  changes 
in  pre-existing  crystalline  plutonic  rocks,  and  by  the  crystal- 
lization of  aqueous  sediments,  for  the  most  part  chemically 
formed  precipitates. 

Mineral  pseudomorphism,  that  is  to  say,  the  assumption  by 
one  mineral  substance  of  the  crystalline  form  of  another,  may 
arise  in  several  ways.  First  of  these  is  the  filling  up  of  a 
mould  left  by  the  solution  or  decomposition  of  an  imbedded 
crystal,  a  process  which  sometimes  takes  place  in  mineral  veins, 
where  the  processes  of  solution  and  deposition  can  be  freely 
carried  on.  Allied  to  this  is  the  mineralization  of  organic 
remains,  where  carbonate  of  lime  or  silica,  for  example,  fills 
the  pores  of  wood.  When  subsequent  decay  removes  the 
woody  tissue,  the  vacant  spaces  may,  in  their  turn,  be  filled  by 
the  same  or  another  species.*  In  the  second  place  we  may 
consider  pseudomorphs  from  alteration,  which  are  the  result  of 
a  gradual  change  in  the  composition  of  a  mineral  species.  This 
process  is  exemplified  in  the  conversion  of  feldspar  into  kaolin 
by  the  loss  of  its  alkali  and  a  portion  of  silica,  and  the  fixa- 
tion of  water,  or  in  the  change  of  chalybite  into  linionite  by 
the  loss  of  carbonic  acid  and  the  absorption  of  water  and 
oxygen. 

*  Hunt  on  the  Silicification  of  Fossils,  Canadian  Naturalist,  New  Series, 
I.  46. 


XIII. ]  ORIGIN   OF  CRYSTALLINE  ROCKS.  287 

The  doctrine  of  pseudomorphism  by  alteration,  as  taught  by 
Gustaf  Rose,  Haidinger,  Blum,  Volger,  Rammelsberg,  Dana, 
Bischof,  and  many  others,  leads  them,  however,  to  admit  still 
greater  and  more  remarkable  changes  than  these,  and  to  main- 
tain the  possibility  of  converting  almost  any  silicate  into  any 
other.  Thus,  by  referring  to  the  pages  of  Bischof 's  Chemical 
Geology,  it  will  be  found  that  serpentine  is  said  to  exist  as  a 
pseudomorph  after  augite,  hornblende,  chrysolite,  chondrodite, 
garnet,  mica,  and  probably  also  after  labradorite  and  even 
orthoclase.  Serpentine  rock  or  ophiolite  is  supposed  to  have 
resulted,  in  different  cases,  from  the  alteration  of  hornblende- 
rock,  diorite,  granulite,  and  even  granite.  Not  only  silicates  of 
protoxides  and  aluminous  silicates  are  conceived  to  be  capable 
of  this  transformation,  but  probably  also  quartz  itself ;  at  least 
Blum  asserts  that  meerschaum,  a  closely  related  silicate  of 
magnesia,  which  sometimes  accompanies  serpentine,  results 
from  the  alteration  of  flint ;  while  according  to  Rose,  serpen- 
tine may  even  be  produced  from  dolomite,  which  we  are  told 
is  itself  produced  by  the  alteration  of  limestone.  But  this  is 
not  all,  —  feldspar  may  replace  carbonate  of  lime,  and  carbon- 
ate of  lime,  feldspar ;  so  that,  according  to  Volger,  some  gneis- 
soid  limestones  are  probably  formed  from  gneiss  by  the  sub- 
stitution of  calcite  for  orthoclase.  In  this  way,  we  are  led 
from  gneiss  or  granite  to  limestone,  from  limestone  to  dolomite, 
and  from  dolomite  to  serpentine,  or,  more  directly,  from  gran- 
ite, granulite,  or  diorite  to  serpentine  at  once,  without  passing 
through  the  intermediate  stages  of  limestone  and  dolomite,  till 
we  are  ready  to  exclaim  in  the  words  of  Goethe,  — 

"  Mich  angatigt  das  Verfangliche 
Im  widrigen  Geschwatz, 
Wo  Nichts  verharret,  Alles  flieht, 
Wo  schon  verschwunden  was  man  sieht,"* 

which  we  may  thus  translate  :  "  I  am  vexed  with  the  sophistry 
in  their  contrary  jargon,  where  nothing  endures,  but  all  is 
fugitive,  and  where  what  we  see  has  already  passed  away." 

Chinesisch-Deutsche  Jahres  und  Tages-Zeiten,  XI. 


288  ORIGIN   OF   CRYSTALLINE  ROCKS.  [XIII. ^ 

By  far  the  greater  number  of  cases  on  which  this  general 
theory  of  pseudomorphism  by  a  slow  process  of  alteration  in 
minerals  has  been  based  are,  as  I  shall  endeavor  to  show,  ex- 
amples of  the  phenomenon  of  mineral  envelopment,  so  well 
studied  by  Delesse  in  his  essay  on  Pseudomorphs,*  and  may 
be  considered  under  two  heads  :  first,  that  of  symmetrical 
envelopment,  in  which  one  mineral  species  is  so  enclosed 
within  the  other  that  the  two  appear  to  form  a  single  crystal- 
line individual.  Examples  of  this  are  seen  when  prisms  of 
cj^anite  are  surrounded  by  staurolite,  or  staurolite  crystals  com- 
pletely enveloped  in  those  of  cyanite,  the  vertical  axes  of  the 
two  prisms  corresponding.  Similar  cases  are  seen  in  the  en- 
closure of  a  prism  of  red  in  an  envelope  of  green  tourmaline, 
of  allamte  in  epidote,  and  of  various  minerals  of  the  pyrox- 
ene group  in  one  another.  The  occurrence  of  muscovite  in 
lepidolite,  and  of  margarodite  in  lepidomelane,  or  the  inverse, 
are  well-known  examples,  and,  according  to  Scheerer,  the  crys- 
tallization of  serpentine  around  a  nucleus  of  olivine  is  a  similar 
case.  This  phenomenon  of  symmetrical  envelopment,  as  re- 
marked by  Delesse,  shows  itself  with  species  which  are  gener- 
ally isomorphous  or  homceomorphous,  and  of  related  chemical 
composition.  Allied  to  this  is  the  repeated  alternation  of  crys- 
talline laminae  of  related  species,  as  in  perthite,  the  crystalline 
cleavable  masses  of  which  consist  of  thin,  alternating  layers  of 
orthoclase  and  albite. 

Very  unlike  to  the  above  are  those  cases  of  envelopment  in 
which  no  relations  of  crystalline  symmetry  nor  of  similar 
chemical  constitution  can  be  traced.  Examples  of  this  kind 
are  seen  in  garnet  crystals,  the  walls  of  which  are  shells, 
sometimes  no  thicker  than  paper,  enclosing,  in  different  exam- 
ples, crystalline  carbonate  of  lime,  epidote,  chlorite,  or  quartz. 
In  like  manner,  crystalline  shells  of  leucite  enclose  feldspar, 
hollow  prisms  of  tourmaline  are  filled  with  crystals  of  mica  or 
with  hydrous  peroxide  of  iron,  and  crystals  of  beryl  with  a 
granular  mixture  of  orthoclase  and  quartz,  holding  small  crys- 
tals of  garnet  and  tourmaline,  a  composition  identical  with  the 
*  Annales  des  Mines  (5),  XVI.  317-392. 


XIII.]  ORIGIN  OF  CRYSTALLINE   ROCKS.  289 

enclosing  granitic  vein-stone.*  Similar  shells  of  galenite  and 
of  zircon,  having  the  external  forms  of  these  species,  are  also 
found  filled  with  calcite.  In  many  of  these  cases  the  process 
seems  to  have  been  first  the  formation  of  a  hollow  mould  or 
skeleton-crystal  (a  phenomenon  sometimes  observed  in  salts 
crystallizing  from  solutions),  the  cavity  being  subsequently 
filled  with  other  matters.  (Ante,  page  212.)  Such  a  process 
is  conceivable  in  free  crystals  formed  in  veins,  as,  for  example, 
galenite,  zircon,  tourmaline,  beryl,  and  some  examples  of  gar- 
net, but  is  not  so  intelligible  in  the  case  of  those  garnets  im- 
bedded in  mica-schist,  studied  by  Delesse,  which  enclosed 
within  their  crystalline  shells  irregular  masses  of  white  quartz, 
with  some  little  admixture  of  garnet.  Delesse  conceives  these 
and  similar  cases  to  be  produced  by  a  process  analogous  to  that 
seen  in  the  crystallizations  of  calcite  in  the  Fontainebleau  sand- 
stone ;  where  the  quartz  grains,  mechanically  enclosed  in  well- 
defined  rhombohedral  crystals,  equal,  according  to  him,  sixty- 
five  per  cent  of  the  mass.  Very  similar  to  the'se  are  the  crys- 
tals with  the  form  of  orthoclase,  which  sometimes  consist  in 
large  part  of  a  granular  mixture  of  quartz,  mica,  and  ortho- 
clase, with  a  little  cassiterite,  and  in  other  cases  contain  two 
thirds  their  weight  of  the  latter  mineral,  with  an  admixture  of 
orthoclase  and  quartz.  Crystals  with  the  form  of  scapolite, 
but  made  up,  in  a  great  part,  of  mica,  seem  to  be  like  cases  of 
envelopment,  in  which  a  small  proportion  of  one  substance  in 
the  act  of  crystallization  compels  into  its  own  crystalline  form 
a  large  portion  of  some  foreign  material,  which  may  even  so 
mask  the  crystallizing  element  that  this  becomes  overlooked,  as 
of  secondary  importance.  The  substance  which,  under  the 
name  of  houghite,  has  been  described  as  an  altered  spinel,  is 
found  by  analysis  to  be  an  admixture  of  vollknerite  with  a 
variable  proportion  of  spinel,  which,  in  some  specimens,  does 
not  exceed  eight  per  cent,  but  to  which,  nevertheless,  these 
crystalloids  (to  use  the  term  suggested  by  Naumann)  appear  to 
owe  their  more  or  less  complete  octohedral  form.t 

*  Report  Geol.  Survey  of  Canada,  1866,  p.  189. 
t  Ibid.,  pp.  189,  213  ;  American  Journal  of  Science  (3),  I.  188. 
13  s 


290  ORIGIN   OF   CRYSTALLINE  ROCKS.  [XIII. 

The  above  characteristic  examples  of  symmetrical  and  asym- 
metrical envelopment  are  cited  from  a  great  number  of  others 
which  might  have  been  mentioned.  Very  many  of  these  are 
by  the  pseudomorphists  regarded  as  results  of  partial  altera- 
tion-. Thus,  in  the  case  of  associated  crystals  of  andalusite 
and  cyanite,  Bischof  does  not  hesitate  to  maintain  the  deriva- 
tion from  andalusite  of  the  latter  species  by  an  elimination  of 
quartz ;  more  than  this,  as  the  andalusite  in  question  occurs  in 
a  granite-like  rock,  he  suggests  that  itself  is  a  product  of  the 
alteration  of  orthoclase.  In  like  manner  the  mica,  which  in 
some  cases  coats  tourmaline,  and  in  others  fills  hollow  prisms 
of  this  mineral,  is  supposed  to  result  from  a  subsequent  altera- 
tion of  crystallized  tourmaline.  So  in  the  case  of  shells  of 
leucite  filled  with  feldspar,  or  of  garnet  enclosing  epidote,  or 
chlorite,  or  quartz,  a  similar  transformation  of  the  interior  is 
supposed  to  have  been  mysteriously  effected,  while  the  external 
portion  of  the  crystal  remains  intact.  Again,  the  aggregates 
of  cassiterile,  quartz,  and  orthoclase,  having  the  form  of  the  lat- 
ter, are,  by  Bischof  and  his  school,  looked  upon  as  results  of 
a  partial  alteration  of  previously  formed  orthoclase  crystals. 
It  needed  only  to  extend  this  view  to  the  crystals  of  calcite 
enclosing  sand-grains,  and  regard  these  as  the  result  of  a  par- 
tial alteration  of  the  carbonate  of  lime.  There  is  absolutely 
no  proof  that  these  hard  crystalline  substances  can  undergo  the 
changes  supposed,  or  can  be  absorbed  and  modified  like  the 
tissues  of  a  living  organism.  It  may,  moreover,  be  confidently 
affirmed  that  the  obvious  facts  of  envelopment  are  adequate  to 
explain  all  the  cases  of  association  upon  which  this  hypothesis 
of  pseudomorphism  by  alteration  has  been  based.  Why  the 
change  should  extend  to  some  parts  of  a  crystal  and  not  to 
others,  why  in  some  cases  the  exterior  of  the  crystal  is  altered, 
while  in  others  the  centre  alone  is  removed  and  replaced  by  a 
different  material,  are  questions  which  the  advocates  of  this 
fanciful  hypothesis  have  not  explained.  As  taught  by  Blum 
and  Bischof,  however,  these  views  of  the  alteration  of  mineral 
species  have  not  only  been  generally  accepted,  but  have  formed 
the  basis  of  the  generally  received  theory  of  rock-metamor- 
phism. 


XIII. ]  ORIGIN  OF  CRYSTALLINE  ROCKS.  291 

Protests  against  the  views  of  this  school  have,  however,  not 
been  wanting.  Scheerer,  in  1846,  in  his  researches  in  Polymeric 
Isomorphism,*  attempted  to  show  that  iolite  and  aspasiolite, 
a  hydrous  species  which  had  been  looked  upon  as  resulting 
from  its  alteration,  were  isomorphous  species  crystallizing  to- 
gether, and,  in  like  manner,  that  the  association  of  chrysolite 
and  serpentine  in  the  same  crystal,  at  Snarum  in  Norway,  was 
a  case  of  envelopment  of  two  isomorphous  species.  In  both 
of  these  instances  he  maintained  the  existence  of  isomorphous 
relations  between  silicates  in  which  3HO  replace  MgO.  He 
hence  rejected  the  view  of  Gustaf  Rose,  that  these  serpentine 
crystals  were  results  of  the  alteration  of  chrysolite,  and  sup- 
ported his  own  by  reasons  drawn  from  the  conditions  in  which 
the  crystals  occur.  In  1853  I  took  up  this  question  and  en- 
deavored to  show  that  these  cases  of  isomorphism  described  by 
Scheerer  entered  into  a  more  general  law  of  isomorphism, 
pointed  out  by  me  among  homologous  compounds  differing  in 
their  formulas  by  7tM202  (M  =  hydrogen  or  a  metal).  I  in- 
sisted, moreover,  on  its  bearing  upon  the  received  views  of  the 
alteration  of  minerals,  and  remarked :  "  The  generally  admitted 
notions  of  pseudomorphism  seem  to  have  originated  in  a  too 
exclusive  plutonism,  and  require  such  varied  hypotheses  to 
explain  the  different  cases,  that  we  are  led  to  seek  for  some 
more  simple  explanation,  and  to  find  it,  in  many  instances,  in 
the  association  and  crystallizing  together  of  homologous  and 
isomorphous  species."  t  Subsequently,  in  1860,  I 'combated 
the  view  of  Bischof,  adopted  by  Dana,  that  "regional  meta- 
morphism  is  pseudomorphism  on  a  grand  scale,"  in  the  follow- 
ing terms :  — 

"  The  ingenious  speculations  of  Bischof  and  others,  on  the  pos- 
sible alteration  of  mineral  species  by  the  action  of  various  saline 
and  alkaline  solutions,  may  pass  for  what  they  are  worth,  although 
we  are  satisfied  that  by  far  the  greater  part  of  the  so-called  cases 
of  pseudomorphism  in  silicates  are  purely  imaginary,  and,  when 
real,  are  but  local  and  accidental  phenomena.  Bischof  s  notion  of 

*  Pogg.  Annal.,  LXVIII.  319. 

f  American  Journal  of  Science  (2),  XVI.  218. 


292  ORIGIN   OF  CRYSTALLINE  ROCKS.  [XIII. 

the  pseudomorphism  of  silicates  like  feldspars  and  pyroxenes  pre- 
supposes the  existence  of  crystalline  rocks,  whose  generation  this 
neptunist  never  attempts  to  explain,  but  takes  his  starting-point 
from  a  plutonic  basis." 

I  then  asserted  that  the  problem  to  be  solved  in  regional 
metarnorphism  is  the  conversion  of  sedimentary  strata,  "  de- 
rived by  chemical  and  mechanical  agencies  from  the  ocean- 
waters  and  pre-existing  crystalline  rocks  into  aggregations  of 
crystalline  silicates.  These  rnetamorphic  rocks,  once  formed, 
are  liable  to  alteration  only  by  local  and  superficial  agencies, 
and  are  not,  like  the  tissues  of  a  living  organism,  subject  to 
incessant  transformations,  the  pseudomorphism  of  Bischof."  * 

I  had  not,  at  that  time,  seen  the  essay  by  Delesse  on  Pseudo- 
morphs,  already  referred  to,  published  in  1859,  in  which  he 
maintained  views  similar  to  those  set  forth  by  me  in  1853  and 
1860,  declaring  that  much  of  what  had  been  regarded  as 
pseudomorphism  had  no  other  basis  than  the  observed  asso- 
ciations of  minerals,  and  that  often  "  the  so-called  metamor- 
phism  finds  its  natural  explanation  in  envelopment."  These 
views  he  ably  and  ingeniously  defended  by  a  careful  discussion 
of  the  whole  range  of  facts  belonging  to  the  history  of  the 
subject. 

My  own  expression  of  opinion  on  this  question,  in  1853, 
had  been  adversely  criticised,  and  I  had  been  charged  with  a 
want  of  comprehension  of  the  question.  It  was,  therefore, 
with  no  small  pleasure,  that  I  not  only  saw  my  views  so  ably 
supported  by  Delesse,  but  read  the  language  of  Carl  Friedrich 
Naumann,  who  in  1861  wrote  to  Delesse  as  follows,  referring 
to  his  essay  just  noticed  :  — 

"  You  have  rendered  a  veritable  service  to  science  in  restricting 
pseudomorphs  to  their  true  limits,  and  separating  what  had  been 
erroneously  united  to  them.  As  you  have  remarked,  envelopments 
have,  for  the  most  part,  nothing  in  common  with  pseudomorphs, 
and  it  is  inconceivable  that  they  have  been  united  by  so  many  min- 
eralogists and  geologists.  It  appears  to  me,  moreover,  that  they 
commit  an  analogous  error,  when  they  regard  gneisses,  amphibo- 

*  American  Journal  of  Science  (2),  XXX.  135. 


XIII.]  ORIGIN   OF  CRYSTALLINE  ROCKS.  293 

lites,  etc.,  as  being,  all  of  them,  the  results  of  metamorphic  epi- 
genesis,  and  not  original  rocks.  It  is  precisely  because  pseudomor- 
phism has  been  so  often  confounded  with  metamorphism,  that  this 
error  has  found  acceptance.  I  only  admit  a  pseudomorph  where 
there  is  some  crystal  the  form  of  which  has  been  preserved.  There 
are  very  many  metamorphic  substances  which  are  in  no  sense  of 
the  word,  pseudomorphs.  Had  the  name  of  crystalloid  been  chosen, 
instead  of  pseudomorph,  this  confusion  would  certainly  have  never 
found  its  way  into  the  science.  I  think,  with  you,  that  the  envel- 
opment of  two  minerals  is  most  generally  explained  by  a  contem- 
poraneous and  original  crystallization.  Secondary  envelopments, 
however,  exist,  and  such  may  be  called  pseudomorphs  or  crystal- 
loids, if  they  reproduce  exactly  the  form  of  the  crystal  enveloped, 
whether  this  last  still  remains,  or  has  entirely  disappeared."  * 

It  is  unnecessary  to  remark  that  the  view  of  Delesse  and 
Kaumann — namely,  that  the  so-called  cases  of  pseudomorphism, 
on  which  the  theory  of  metamorphism  by  alteration  has  been 
built,  are,  for  the  most  part,  examples  of  association  and  envel- 
opment, and  the  result  of  a  contemporaneous  and  original 
crystallization  —  is  identical  with  the  view  suggested  by 
Scheerer,  and  generalized  by  myself  long  before,  when,  in  1853, 
I  sought  to  explain  the  phenomena  in  question  by  "  the  associa- 
tion and  crystallizing  together  of  homologous  and  isomorphous 
species." 

Later,  in  1862,  I  wrote  as  follows  :  — 

"  Pseudomorphism,  which  is  the  change  of  one  mineral  species 
into  another  by  the  introduction  or  the  elimination  of  some  element 
or  elements,  presupposes  metamorphism  (i.  e.  metamorphic  or  crys- 
talline rocks),  since  only  definite  mineral  species  can  be  the  subjects 
of  this  process.  To  confound  metamorphism  with  pseudomorphism, 
as  Bischof  and  others  after  him  have  done,  is  therefore  an  error.  It 
may  be  further  remarked,  that,  although  certain  pseudomorphic 
changes  may  take  place  in  some  mineral  species,  in  veins  and  near 
the  surface,  the  alteration  of  great  masses  of  silicated  rocks  by  such 
a  process  is  as  yet  an  unproved  hypothesis."  t 

»  Bull.  Soc.  Geol.  de  France  (2),  XVIII.  678.      • 

t  Descriptive  Catalogue,  Crystalline  Rocks  of  Canada,  p.  80,  London  Ex- 
hibition, 1862  ;  also  Canadian  Naturalist,  VII.  262  ;  Dublin  Quar.  Journal, 
July,  1863;  and  American  Journal  of  Science  (2),  XXXVI.  218. 


294  ORIGIN   OF   CRYSTALLINE  ROCKS.  [XIII. 

Thus  this  unproved  theory  of  pseudomorphism,  as  taught  by 
Bischof,  does  not,  even  if  admitted  to  its  fullest  extent,  advance 
us  a  single  step  towards  a  solution  of  the  problem  of  the  origin 
of  the  various  silicates  which,  singly  or  intermingled,  make  up 
beds  in  the  crystalline  schists.  Granting,  for  the  sake  of  argu- 
ment, that  serpentine  results  from  the  alteration  of  chrysolite  or 
labradorite,  and  steatite  or  chlorite  from  hornblende,  the  origin 
of  these  anhydrous  silicates,  which  are  the  subjects  of  the 
supposed  change,  is  still  unaccounted  for.  The  explanation  of 
this  short-sightedness  is  not  far  to-  seek  ;  as  already  remarked, 
Bischof,  although  a  professed  neptunist,  starts  from  a  plutonic 
basis. 

[The  notion  of  the  plutonic  origin  of  crystalline  stratified 
rocks  has  in  fact  found  many  advocates,  as  may  be  seen  by 
reference  to  pages  of  Naumann's  Lehrbuch  der  Geognosie. 
This  learned  author  himself  speaks  of  them  as  "those  enig- 
matical deepest-lying  rocks  which  resemble  sedimentary  strata 
in  possessing  more  or  less  perfect  stratification,  while  resem- 
bling eruptive  rocks  in  mineral  composition  and  crystalline 
structure"  (loc.  cit.,  Yol.  II.  p.  8,  et  seq.).  He  declares  them  to 
be  neither  sedimentary  nor  eruptive  in  the  ordinary  sense  of 
those  terms ;  and  evidently  leans  to  the  notion,  of  which  he 
speaks  with  favor,  that  they  are  in  some  way  the  first-solidified 
portions  of  the  once  molten  globe.  He  elsewhere  says  that  the 
solidification  being  from  the  surface  downwards,  the  lowest  of 
these  rocks  must  be  the  newest,  except  so  far  as  eruptive  masses 
may  break  up  through  the  crust.  Tchitatchef,  from  his  recent 
researches  in  Asia  Minor,  holds  to  Naumann's  view  as  to  the 
plutonic  origin  of  the  gneissic  rocks  of  that  region.  The  most 
recent  and  most  explicit  statement  of  this  view  of  the  plutonic 
origin  of  these  rocks  is  that  put  forth  by  Macfarlane,  in  a 
learned  essay  on  The  Eruptive  and  Primary  Rocks,  in  the 
Canadian  Naturalist  for  1864.  He  conceives  that  the  structure 
in  these  rocks  may  have  been  generated  by  currents  in  the 
molten  mass  of  the  globe  ;  and,  further,  that  the  once-formed 
crust  may  have  had  a  different  rate  of  rotation  from  the  liquid 
below ;  from  which  also  would  result  a  stratiform  arrangement 


XIIL]  ORIGIN  OF  CRYSTALLINE  ROCKS.  295 

in  the  elements  of  the  solidifying  layers,  such  as  is  seen  in  many 
slags,  and  in  certain  eruptive  rocks.  (Ante,  page  186.)  Add  to 
this  notion  that  of  the  separation  of  the  fluid  or,  rather,  viscid 
mass  into  two  or  more  layers  of  different  composition  and 
density  (ante,  page  3),  and  we  might  have  generated  from 
them,  by  their  solidification  under  the  above  conditions,  the 
various  types  of  stratiform  feldspathic,  hornblendic,  and  chrys- 
olitic  rocks,  which  would  afterwards  be  penetrated  by  injections 
from  the  yet  liquid  portions  below.  If  now  we  imagine  the 
various  plutonic  rocks  thus,  formed,  both  stratified  and  unstrati- 
ned,  to  be  the  subjects  of  epigenic  or  pseudomorphous  changes, 
by  which  some  beds  or  masses  were  converted  in  serpentine  or 
into  steatitic  or  chloritic  rocks,  while  others  were  changed  into 
limestone,  quartzite,  or  iron-oxide,  we  shall  have  as  clear  a  con- 
ception as  it  is  possible  to  form  of  the  vaguely  defined  views  of 
Naumann,  Bischof,  and  their  school,  as  to  the  origin  of  the 
crystalline  rocks  as  we  now  find  them. 

!Naumann,  while  denying  the  sedimentary  origin  of  the  great 
mass  of  crystalline  schists,  admitted,  however,  the  conversion 
of  younger  uncrystalline  sedimentary  strata,  in  certain  cases, 
into  crystalline  gneisses  and  mica-schists,  resembling  those  of 
the  primary  formations,  and  like  them  subject  to  epigenic 
changes.  That  such  crystalline  rocks  have  ever  been  formed 
from  the  alteration  of  palaeozoic  or  more  recent  sediments, 
except  locally  (pages  18,  298,  and  310),  is,  however,  more  than 
doubtful,  as  will  appear  from  the  examination  of  the  supposed 
examples  of  this  conversion  in  the  preceding  pages  of  this 
paper,  and  also  in  the  following  one  on  the  Geology  of  the 
Alps.  In  connection  with  these  two  papers  are  given  the  views 
of  Giimbel  (page  305)  and  of  Favre  on  this  important  question. 

These  crystalline  rocks,  whatever  their  origin  or  mode  of 
formation,  appear  to  be  in  all  cases  older  than  the  palasozoic 
sediments.  They  belong  to  at  least  three  or  four  geognostically 
discordant  series,  and  are  moreover  occasionally  associated  with 
fragmentary  rocks,  which  render  it  impossible  to  admit  for  them 
any  other  than  an  aqueous  sedimentary  origin,  in  accordance 
with  the  view  already  denned  on  page  286.] 


296  ORIGIN   OF   CRYSTALLINE   ROCKS.  [XIII1 

Whence,  then,  come  these  silicates  of  magnesia,  lime,  and 
iron,  which  are  the  sources  of  the  serpentine,  chrysolite,  pyrox- 
ene, hornblende,  steatite,  and  chlorite,  which  abound  in  these 
rocks  ]  This  is  the  question  which  I  proposed  in  1860,  when, 
after  discussing  the  results  of  my  examinations  of  the  tertiary 
rocks  near  Paris,  containing  layers  of  a  hydrous  silicate  of  mag- 
nesia, related  to  talc  in  composition,  among  unaltered  limestones 
and  clays,  I  remarked  that  it  is  evident  "  such  silicates  may  be 
formed  in  basins  at  the  earth's  surface,  by  reactions  between 
magnesian  solutions  and  dissolved  silica  "  ;  and,  after  some  dis- 
cussion, said  "  further  inquiries  in  this  direction  may  show  to 
what  extent  certain  rocks  composed  of  calcareous  and  mag- 
nesian silicates  may  be  directly  formed  in  the  moist  way."* 
Subsequently,  in  a  paper  on  The  Origin  of  some  Magnesian 
and  Aluminous  Rocks,  printed  in  the  Canadian  Naturalist  for 
June,  1860,t  I  repeated  these  considerations,  referring  to  the 
well-known  fact  that  silicates  of  lime,  magnesia,  and  iron-oxide 
are  deposited  during  the  evaporation  of  natural  waters,  includ- 
ing those  of  alkaline  springs  and  of  the  Ottawa  River.  Having 
described  the  mode  of  occurrence  of  the  magnesian  silicate, 
sepiolite,  in  the  Paris  basin,  and  the  related  quincite,  containing 
some  iron-oxide,  and  disseminated  in  limestone,  I  suggested  that 
while  steatite  has  been  derived  from  a  compound  like  sepiolite, 
the  source  of  serpentine  was  to  be  sought  in  another  silicate 
richer  in  magnesia ;  and,  moreover,  that  chlorite  (unless  the 
result  of  a  subsequent  reaction  between  clay  and  carbonate  of 
magnesia)  was  directly  formed  by  a  process  analogous  to  that 
which,  according  to  Scheerer,  has,  in  recent  times,  caused  the 
deposition  from  waters  of  neolite,  —  a  hydrous  alumino-mag- 
nesian  silicate,  approaching  to  chlorite  in  composition,  J  "  the 
type  of  a  reaction  which  formerly  generated  beds  of  chlorite,  in 
the  same  way  as  those  of  sepiolite  or  talc."  Delesse,  subse- 
quently, in  186.1,  in  his  essay  on  Metamorphism,  insisted  upon 
the  sepiolite  or  so-called  magnesian  marls,  as  probably  the 

*  American  Journal  of  Science  (2),  XXIX.  284;  also  (2),  XL.  49. 
t  Ibid.  (2),  XXXII.  286. 
J  Pogg.  Annal.,  LXX1.  288. 


XIII.]  ORIGIN   OF  CRYSTALLINE  ROCKS.  297 

source  of  steatite,  and  suggested  the  derivation  of  serpentine, 
chlorite,  and  other  related  minerals  of  the  crystalline  schists, 
from  deposits  approaching  these  marls  in  composition.*  He 
recalled,  also,  the  occurrence  of  chromic  oxide,  a  frequent  ac- 
companiment of  these  rnagnesian  minerals,  in  the  hydrated  iron 
ores  of  the  same  geological  horizon  with  the  magnesian  marls 
in  France.  Delesse  did  not,  however,  attempt  to  account  for 
the  origin  of  these  deposits  of  magnesian  marls,  in  explanation 
of  which  I  afterwards  verified  Bischof 's  observations  on  the 
sparing  solubility  of  silicate  of  magnesia,  and  showed  that  sili- 
cate of  soda,  or  even  artificial  hydrated  silicate  of  lime,  when 
added  to  waters  containing  magnesian  chloride  or  sulphate,  gives 
rise,  by  double  decomposition,  to  a  very  insoluble  magnesian 
silicate.  (Ante,  page  122.) 

To  explain  the  generation  of  silicates  like  the  feldspars, 
scapolite,  garnet,  and  saussurite,  I  suggested  that  double  alu- 
minous silicates,  allied  to  the  zeolites,  might  have  been  formed, 
and  subsequently  rendered  anhydrous.  The  production  of 
zeolitic  minerals  observed  by  Daubree,  at  Plombieres  and  Lux- 
euil,  by  the  action  of  a  silicated  alkaline  water  on  the  masonry 
of  ancient  Roman  baths,  was  appealed  to  by  way  of  illustra- 
tion. (Ante,  pages  25  and  205.)  It  has  been  shown  by  Daubree 
that  the  elements  of  the  zeolites  were  derived  in  part  from  the 
waters,  and  in  part  from  the  mortar,  and  even  the  clay  of  the 
bricks,  which  had  been  attacked,  and  had  entered  into  com- 
bination with  the  soluble  matters  of  the  water  to  form  chaba- 
zite.  I,  however,  at  the  same  time  pointed  out  another  source 
of  silicated  minerals,  upon  which  I  had  insisted  since  1857, 
namely,  the  reaction  between  silicious  or  argillaceous  matters  and 
earthy  carbonates  in  the  presence  of  alkaline  solutions.  Nu- 
merous experiments  showed  that  when  solutions  of  an  alkaline 
carbonate  were  heated  with  a  mixture  of  silica  and  carbonate 
of  magnesia,  the  alkaline  silicate  formed  acted  upon  the  latter, 
yielding  a  silicate  of  magnesia,  and  regenerating  the  alkaline  car- 
bonate ;  which,  without  entering  into  permanent  combination, 
was  the  medium  through  which  the  union  of  the  silica  and  the 

*  Etudes  sur  le  Metamorphisme,  quarto,  pp.  91.   Paris,  1861. 
13* 


298  OKIGIN   OF   CRYSTALLINE   ROCKS.  [XIII. 

magnesia  was  effected.  In  this  way  I  endeavored  to  explain  the 
alteration,  in  the  vicinity  of  a  great  intrusive  mass  of  dolerite, 
of  a  gray  palaeozoic  limestone,  which  contained,  besides  a  little 
carbonate  of  magnesia  and  iron-oxide,  a  portion  of  very  silicious 
matter,  consisting  apparently  of  comminuted  orthoclase  and 
quartz.  In  place  of  this,  there  had  been  developed  in  the  lime- 
stone, near  its  contact  with  the  dolerite,  an  amorphous  greenish 
basic  silicate,  which  had  seemingly  resulted  from  the  union  of 
the  silica  and  alumina  with  the  iron-oxide,  the  magnesia,  and  a 
portion  of  lime.  By  the  crystallization  of  the  products  thus 
generated,  it  was  conceived  that  minerals  like  hornblende, 
garnet,  and  epidote  might  be  developed  in  earthy  sediments, 
and  many  cases  of  local  alteration  explained.  Inasmuch  as  the 
reaction  described  required  the  intervention  of  alkaline  solu- 
tions, rocks  from  which  these  were  excluded  would  escape 
change,  although  the  other  conditions  might  not  be  wanting. 
The  natural  associations  of  minerals,  moreover,  led  me  to  sug- 
gest that  alkaline  solutions  might  favor  the  crystallization  of 
aluminous  silicates,  and  thus  convert  mechanical  sediments  into 
gneisses  and  mica-schists.  The  ingenious  experiments  of  Dau- 
bree  on  the  part  which  solutions  of  alkaline  silicates,  at  ele- 
vated temperatures,  may  play  in  the  formation  of  crystallized 
minerals,  such  as  feldspar  and  pyroxene,  were  posterior  to  my 
early  publications  on  the  subject,  and  fully  justified  the  im- 
portance which,  early  in  1857,  I  attributed  to  the  intervention 
of  alkaline  silicates,  in  the  formation  of  crystalline  silicated 
minerals.*  (Ante,  pages  6  and  25.) 

[While  we  may  not  question  the  regeneration  of  feldspars 
and  zeolites  (which  are  but  hydrated  feldsdars)  by  the  combina- 
tion of  silicates  of  alumina,  like  clay,  with  soluble  alkaline  or 
calcareous  silicates,  it  is  evident  that  this  process  is  not  the 
chief  nor  the  primary  one ;  since  the  existence  of  clay  sup- 
poses the  previous  existence  and  decay  of  feldspars.  The  dep- 
osition of  immense  quantities,  alike  of  orthoclase,  albite,  and 
oligoclase  in  veins  which  are  evidently  of  aqueous  origin,  shows 
that  conditions  have  existed  in  which  the  elements  of  these 
»  Proc.  Royal  Soc.,  May  7,  1857. 


XIII.]  ORIGIN   OF  CRYSTALLINE  ROCKS.  299 

mineral  species  were  abundant  in  solution.  The  relation  be- 
tween these  endogenous  deposits  and  the  great  beds  of  orthoclase 
and  triclinic  feldspar  rocks  is  similar  to  that  between  veins  of 
calcite  and  of  quartz  and  beds  of  marble  and  travertine,  of 
quartzite  and  hornstone.  But  while  the  conditions  in  which 
these  latter  mineral  species  are  deposited  from  solution  are  per- 
petuated to  our  own  time,  those  of  the  deposition  of  feldspars 
and  many  other  species,  whether  in  veins  or  in  beds,  appear  to 
belong  only  to  remote  geological  ages,  and  at  best  are  represented 
in  more  recent  time  only  by  the  production  of  a  few  zeolitic 
minerals.  See  in  this  connection  the  paper  on  Granites  and 
Granitic  Vein-Stones,  XL  of  the  present  volume,  passim,  but 
especially  §§  30,  31,  and  49.] 

While,  however,  there  is  good  reason  to  believe  that  solu- 
tions of  alkaline  silicates  or  carbonates  have  been  efficient 
agents  in  the  crystallization  and  molecular  rearrangement  of 
ancient  sediments,  and  have  also  played  an  important  part  in 
that  local  alteration  of  sedimentary  strata  which  is  often  ob- 
served in  the  vicinity  of  intrusive  rocks,  it  is  clear  to  me  that 
the  agency  of  these  solutions  is  less  universal  than  once  sup- 
posed by  Daubree  and  myself,  and  will  not  account  for  the 
formation  of  various  silicated  rocks  belonging  to  the  crystalline 
schists,  such  as  serpentine,  hornblende,  steatite,  and  chlorite. 
When  I  commenced  the  study  of  these  crystaDine  strata  I  was 
led,  in  accordance  with  the  almost  universally  received  opinion 
of  geologists,  to  regard  them  as  resulting  from  a  subsequent 
alteration  of  palaeozoic  sediments,  which,  according  to  different 
authorities,  were  of  Cambrian,  Silurian,  or  Devonian  age. 
Thus  in  the  Appalachian  region,  as  we  have  already  seen,  they 
have,  on  supposed  stratigraphical  evidence,  been  successively 
placed  at  the  base,  at  the  summit,  and  in  the  middle  of  the 
Cham  plain  division  of  the  New  York  system.  A  careful  chem- 
ical examination  among  the  unaltered  palaeozoic  sediments, 
which  in  Canada  were  looked  upon  as  the  stratigraphical  equiv- 
alents of  the  bands  of  magnesian  silicates  in  these  crystalline 
schists,  showed  me,  however,  no  magnesian  rocks,  except  cer- 
tain silicious  and  ferruginous  dolomites.  From  a  consideration 


300  ORIGIN   OF  CRYSTALLINE  ROCKS.  [XIII. 

of  reactions  which  I  had  observed  to  take  place  in  such  admix- 
tures in  presence  of  heated  alkaline  solutions,  and  from  the 
composition  of  the  basic  silicates  which  I  had  found  to  be 
formed  in  silicious  limestones  near  their  contact  with  eruptive 
rocks,  I  was  led  to  suppose  that  similar  actions,  on  a  grand 
scale,  might  transform  these  silicious  dolomites  of  the  unaltered 
strata  into  crystalline  magnesian  silicates. 

Further  researches,  however,  convinced  me  that  this  view 
was  inapplicable  to  the  crystalline  schists  of  the  Appalachians, 
since,  apart  from  the  geognostical  considerations  set  forth  in 
the  previous  part  of  this  paper,  I  found  that  these  same  crys- 
talline strata  hold  beds  of  quartzose  dolomite  and  magnesian 
carbonate,  associated  in  such  intimate  relations  with  beds  of 
serpentine,  diallage,  and  steatite,  as  to  forbid  the  notion  that 
these  silicates  could  have  been  generated  by  any  transforma- 
tions or  chemical  rearrangement  of  mixtures  like  the  accom- 
panying beds  of  quartzose  magnesian  carbonates.  Hence  it 
was  that  already,  in  1860,  as  shown  above,  I  announced  my 
conclusion  that  serpentine,  chlorite,  and  steatite  had  been  de- 
rived from  silicates  like  sepiolite,  directly  formed  in  waters  at 
the  earth's  surface,  and  that  the  crystalline  schists  had  resulted 
from  the  consolidation  of  previously  formed  sediments,  partly 
chemical  and  partly  mechanical  in  their  origin.  The  latter 
being  chiefly  silico-aluminous,  took,  in  part,  the  forms  of  gneiss 
and  mica-schists,  while  from  the  more  argillaceous  strata,  poorer 
in  alkali,  much  of  the  aluminous  silicate  crystallized  as  anda- 
lusite,  staurolite,  cyanite,  and  garnet.  These  views  were  reit- 
erated in  1863,*  and  further  in  1864,  in  the  following  lan- 
guage, as  regards  the  chemically  formed  sediments  :  "  Steatite, 
serpentine,  pyroxene,  hornblende,  and  in  many  cases  garnet, 
epidote,  and  other  silicated  minerals,  are  formed  by  a  crystalli- 
zation and  molecular  rearrangement  of  silicates  generated  by 
chemical  processes  in  waters  at  the  earth's  surface."  t  Their 
alteration  and  crystallization  was  compared  to  that  of  the 

*  Geology  of  Canada,  pp.  577  -  581. 

f  American  Journal  of  Science  (2),  XXXVII.  266  ;  and  XXXVII.  183. 


XIIL]  ORIGIN  OF  CRYSTALLINE  ROCKS.  301 

mechanically   formed    feldspathic,    silicious,    and   argillaceous 
sediments  just  mentioned. 

The  direct  formation  of  the  crystalline  schists  from  an 
aqueous  magma  is  a  notion  which  belongs  to  an  early  period 
in  geological  theory.  Delabeche  in  1834*  conceived  that  they 
were  thrown  down  as  chemical  deposits  from  the  waters  of  the 
heated  ocean,  after  its  reaction  on  the  crust  of  the  cooling 
globe,  and  before  the  appearance  of  organic  life.  This  view 
was  revived  by  Daubree  in  1860.  Having  sought  to  explain 
the  alteration  of  palaeozoic  strata  of  mechanical  origin  by  the 
action  of  heated  waters,  he  proceeds  to  discuss  the  origin  of 
the  still  more  ancient  crystalline  schists.  The  first  precipitated 
waters,  according  to  him,  acting  on  the  anhydrous  silicates  of 
the  earth's  crust,  at  a  very  elevated  temperature,  and  at  a  great 
pressure  which  he  estimated  at  two  hundred  and  fifty  atmos- 
pheres, formed  a  magma  from  which,  as  it  cooled,  were  suc- 
cessively deposited  the  various  strata  of  the  crystalline  schists. t 
This  hypothesis,  violating,  as  it  does,  all  the  notions  which 
sound  theory  teaches  with  regard  to  the  chemistry  of  a  cooling 
globe,  has,  moreover,  to  encounter  grave  geognostical  difficul- 
ties. The  pre-Cambrian  crystalline  rocks  belong  to  two  or 
more  distinct  systems  of  different  ages,  succeeding  each  other 
in  discordant  stratification.  The  whole  history  of  these  rocks, 
moreover,  shows  that  their  various  alternating  strata  were  de- 
posited, not  as  precipitates  from  a  seething  solution,  but  under 
conditions  of  sedimentation  not  unlike  those  of  more  recent 
times.  In  the  oldest  known  of  them,  the  Laurentian  system, 
great  limestone  formations  are  interstratified  with  gneisses, 
quartzites,  and  even  with  conglomerates.  All  analogy,  more- 
over, leads  us  to  conclude  that,  even  at  this  early  period,  life 
existed  at  the  surface  of  the  planet.  Great  accumulations  of 
iron-oxide,  beds  of  metallic  sulphides  and  of  graphite,  exist  in 
these  oldest  strata,  and  we  know  of  no  other  agency  than  that 
of  organic  matter  capable  of  generating  these  products.  ["  The 
presence  of  graphite,  of  native  iron,  and  of  sulphurets  in  most 

*  Researches  in  Theoretical  Geology,  pp.  297  -  300. 

t  Etudes  et  experiences  synthetiques  sur  le  metamorphisme,  pp.  119  - 121. 


302  ORIGIN   OF   CRYSTALLINE  ROCKS.  [XIII. 

aerolites,  not  to  mention  the  hydrocarbonaceous  matters  which 
they  sometimes  contain,  tells  us  in  unmistakable  language  that 
these  bodies  come  from  a  region  where  vegetable  life  has  per- 
formed a  part  not  unlike  that  which  still  plays  on  our  globe, 
and  even  leads  us  to  hope  for  the  discovery  in  them  of  organic 
forms  which  may  give  us  some  notion  of  life  in  other  worlds 
than  our  own."  *] 

Bischof  had  already  arrived  at  the  conclusion,  which  in  the 
present  state  of  our  knowledge  seems  inevitable,  that  "  all  the 
carbon  yet  known  to  occur  in  a  free  state  can  only  be  regarded 
as  a  product  of  the  decomposition  of  carbonic  acid,  and  as 
derived  from  the  vegetable  kingdom."  He  further  adds,  "  liv- 
ing plants  decompose  carbonic  acid,  dead  organic  matters 
decompose  sulphates,  so  that,  like  carbon,  sulphur  appears  to 
owe  its  existence  in  a  free  state  to  the  organic  kingdom."  *t*  As 
a  decomposition  (deoxidation)  of  sulphates  is  necessary  to  the 
production  of  metallic  sulphides,  the  presence  of  the  latter,  not 
less  than  that  of  free  sulphur  and  free  carbon,  depends  on 
organic  bodies ;  the  part  which  these  play  in  reducing  and 
rendering  soluble  the  peroxide  of  iron,  and  in  the  production 
of  iron-ores,  is,  moreover,  well  known.  It  was,  therefore,  that, 
after  a  careful  study  of  these  ancient  rocks,  I  declared  in  May, 
1858,  that  a  great  mass  of  evidence  "points  to  the  existence 
of  organic  life,  even  during  the  Laurentian  or  so-called  azoic 
period."  J 

This  prediction  was  soon  verified  in  the  discovery  of  the 
Eozoon  Canadense  of  Dawson,  the  organic  character  of  which 
is  now  admitted  by  most  zoologists  and  geologists  of  authority. 
But  with  this  discovery  appeared  another  fact,  which  afforded 
a  signal  verification  of  my  theory  as  to  the  origin  and  mode  of 
deposition  of  serpentine  and  pyroxene.  The  microscopic  and 
chemical  researches  of  Dawson  and  myself  showed  that  the 
calcareous  skeleton  of  this  foraminiferal  organism  was  filled 

*  The  Chemistry  of  the  Earth,  §  19,  in  the  Report  of  Smithsonian  Insti' 
tution  for  1869. 

t  Bischof,  Lehrbuch,  1st  ed.,  II.  95;  English  ed.,  1.  252,  344. 
J  American  Journal  of  Science  (2),  XXV.  436. 


XIII.]  ORIGIN   OF  CRYSTALLINE  ROCKS.  303 

with  the  one  or  the  other  of  these  silicates  in  such  a  manner  as 
to  make  it  evident  that  they  had  replaced  the  sarcode  of  the 
animal,  precisely  as  glauconite  and  similar  silicates  have,  from 
Cambrian  times  to  the  present,  filled  and  injected  more  recent 
foraminiferal  skeletons.  I  recalled,  in  connection  with  this 
discovery,  the  observations  of  Ehrenberg,  Mantell,  and  Bailey, 
and  the  more  recent  ones  of  Pourtales,  to  the  effect  that  glau- 
conite or  some  similar  substance  occasionally  fills  the  spines  of 
Echini,  the  cavities  of  corals  and  millepores,  the  canals  in  the 
shells  of  Balanus,  and  even  forms  casts  of  the  holes  made  by 
burrowing  sponges  (Clionia)  and  worms.  The  significance  of 
these  facts  was  further  illustrated  by  showing  that  the  so- 
called  glauconites  differ  considerably  in  composition,  some  of 
them  containing  more  or  less  alumina  or  magnesia,  and  one 
from  the  tertiary  limestones  near  Paris  being,  according  to 
Berthier,  a  true  serpentine.* 

These  facts  in  the  history  of  Eozoon  were  first  made  known 
by  me  in  May,  1864,  in  the  American  Journal  of  Science,  and 
subsequently  more  in  detail,  February,  1865,  in  a  communi- 
cation to  the  Geological  Society  of  London. t  They  were 
speedily  verified  by  Dr.  Giimbel,  who  was  then  engaged 
in  the  study  of  the  ancient  crystalline  schists  of  Bavaria,  and 
soon  recognized  the  existence,  in  the  limestones  of  the  old 
Hercynian  gneiss,  of  the  characteristic  Eozoon  Canadense, 
injected  with  silicates  in  a  manner  precisely  similar  to  that 
observed  by  Dawson  and  myself. £  Later,  in  1869,  Robert 
Hoffmann  described  the  results  of  a  minute  chemical  examina- 
tion of  the  Eozoon  from  Raspenau,  in  Bohemia,  confirming 
the  previous  observations  in  Canada  and  Bavaria.  He  showed 
that  the  calcareous  shell  of  the  Eozoon,  examined  by  him, 
had  been  injected  by  a  peculiar  silicate,  which  may  be  de- 
scribed as  related  in  composition  both  to  glauconite  and  to 

*  American  Journal  of  Science  (2),  XL.  360  ;  Report  Geol.  Survey  of  Can- 
ada, 1866,  p.  231  ;  and  Quar.  Geol.  Jour.,  XXI.  71. 

t  American  Journal  of  Science  (2),  XXXVII.  431 ;  Quar.  Geol.  Jour.,  XXI. 
67. 

+  Proc.  Royal  Bavar.  Acad.  for  1866  ;  and  Can.  Naturalist,  new  series, 
III.  81. 


304  ORIGIN   OF   CRYSTALLINE   ROCKS.  [XIII. . 

chlorite.  The  masses  of  Eozob'n  he  found  to  be  enclosed  and 
wrapped  around  by  thin  alternating  layers  of  a  green  mag- 
nesian  silicate  allied  to  picrosmine,  and  a  brown  non-magnesian 
mineral,  which  proved  to  be  a  hydrous  silicate  of  alumina, 
ferrous  oxide  and  alkalies,  related  to  fahlunite,  or  more  nearly 
to  jolly te  in  composition.* 

Still  more  recently,  Dr.  Dawson  has  detected  a  crystalline 
silicated  mineral  insoluble  in  dilute  acids,  injecting  the  pores 
of  crinoidal  stems  and  plates  in  a  palaeozoic  limestone  from 
New  Brunswick,  which  is  made  up  of  organic  remains.  This 
silicate,  which,  in  decalcified  specimens,  exhibits  in  a  beautiful 
manner  the  intimate  structure  of  these  ancient  crinoids,  I  have 
found  by  analysis  to  be  a  hydrous  silicate  of  alumina  and 
ferrous  oxide,  with  magnesia  and  alkalies,  closely  related  to 
fahlunite  and  to  jollyte.  The  microscopic  examinations  of  Dr. 
Dawson  show  that  this  silicate  had  injected  the  pores  of  the 
crinoidal  remains  and  some  of  the  interstices  of  the  associated 
shell  fragments  before  the  introduction  of  the  calcite  which 
cements  the  mass.  I  have  since  found  a  silicate  almost  identi- 
cal with  this  occurring  under  similar  conditions  in  a  Silurian 
limestone  said  to  be  from  Llangwyllog  in  Anglesea.t 

Gumbel,  meanwhile,  in  the  essay  on  the  Laurentian  rocks  of 
Bavaria,  in  1866,  already  referred  to,  fully  recognized  the  truth 
of  the  views  which  I  had  put  forward,  both  with  regard  to  the 
mineralogy  of  Eozob'n  and  to  the  origin  of  the  crystalline 
schists.  His  results  are  still  further  detailed  in  his  Geognost. 
Beschreibung  des  bstbayerisches  Grenzegebirges,  1868,  p.  833. 
Credner,  moreover,  as  he  tells  us,J  had  already,  from  his  min- 
eralogical  and  lithological  studies,  been  led  to  admit  my  views 
as  to  the  original  formation  of  serpentine,  pyroxene,  and  sim- 
ilar silicates  (which  he  cites  from  my  paper  of  1865,  above 
referred  to  §),  when  he  found  that  Gumbel  had  arrived  at 

*  Jour  fur.  Prakt.  Chem.,  May,  1869 ;  and  American  Journal  of  Science 
(3),  I.  378; 

t  American  Journal  of  Science  (3),  I.  379,  and  II.  57. 

£  Hermann  Credner;  die  Gleiderung  der  Eozoischen  Formation sgruppe 
Nord  Amerikas.  Halle,  1869. 

§  That  in  the  Quar.  Geol.  Jour.,  XXI.  67. 


XIII.]  ORIGIN   OF  CRYSTALLINE  ROCKS.  305 

similar  conclusions.  The  views  of  the  latter,  as  cited  by 
Credner  from  the  work  just  referred  to,  are  in  substance  as 
follows  :  the  crystalline  schists,  with  their  interstratified  lay- 
ers, have  all  the  characters  of  altered  sedimentary  deposits, 
and  from  their  mode  of  occurrence  cannot  be  of  igneous  ori- 
gin, nor  the  result  of  epigenic  action.  The  originally  formed 
sediments  are  conceived  to  have  been  amorphous,  and  under 
moderate  heat  and  pressure  to  have  arranged  themselves,  and 
crystallized,  generating  various  mineral  species  in  their  midst 
by  a  change,  which,  to  distinguish  it  from  metamorphism  by 
an  epigenic  process,  Giimbel  happily  designates  diagenesis* 

It  is  unnecessary  to  remark  that  these  views,  the  conclusions 
from  the  recent  studies  of  Giimbel  in  Germany  and  Credner  in 
North  America,  are  identical  with  those  put  forth  by  me  in 
1860.t 

[*  The  following  is  extracted  from  an  essay  by  the  author  in  the  Report 
of  the  Smithsonian  Institution  for  1869,  on  The  Chemistry  of  the  Earth, 
§  33  :  "  The  gradual  transformation  of  amorphous  precipitates  under  water 
into  crystalline  aggregates,  so  often  observed  in  the  laboratory,  appears  to 
depend  upon  partial  solution  and  re-deposition  of  the  material,  which  must 
not  be  entirely  insoluble  in  the  surrounding  liquid.  If  the  solvent  power  of 
this  be  reduced,  the  dissolved  portions  are  deposited  on  certain  particles 
rather  than  others.  By  a  subsequent  exaltation  of  the  solvent  power  of  the 
liquid,  solution  of  a  further  portion  takes  place,  and  this,  in  its  turn,  is  de- 
posited around  the  nuclei  already  formed,  which  are  thus  augmented  at  the 
expense  of  the  smaller  particles,  until  these  at  length  disappear,  being  gath- 
ered to  the  crystalline  centres.  Such  a  process,  which  has  been  studied  by 
H.  Deville,  suffices,  under  the  influence  of  the  changing  temperature  of  the 
seasons,  to  convert  many  fine  precipitates  into  crystalline  aggregates,  by  the 
aid  of  liquids  of  slight  solvent  powers.  A  similar  agency  may  be  supposed 
to  have  effected  the  crystallization  of  buried  sediments,  and  changes  in  the 
solvent  power  of  the  permeating  water  might  be  due  either  to  variations  of 
temperature  or  of  pressure.  Simultaneously  with  this  process  one  of  chemical 
uuion  of  heterogeneous  elements  may  go  on,  and  in  this  way,  for  example,  we 
may  suppose  the  carbonates  of  lime  and  magnesia  become  united  to  form 
dolomite  or  magnesian  limestone."] 

[t  Since  the  first  publication  of  the  above  address  I  have  received  in  a  pri- 
vate letter  from  Giimbel  the  following  re-statement  of  his  views  as  to  the 
origin  of  crystalline  rocks  :  "  I  have  seen  no  occasion  to  change  my  opinions, 
which  are,  I  believe,  identical  with  your  own.  I  do  not  maintain  a  metamor- 
phic  origin  for  the  primitive  rocks ;  for,  although  these  are  certainly  much 
altered,  there  are  no  firm  and  consolidated  rocks  which  are  not  so.  They 
were  formed  like,  for  example,  the  limestones  of  more  recent  periods;  these 

T 


306  ORIGIN   OF  CRYSTALLINE  ROCKS.  [XIII. 

At  the  early  periods  in  which  the  materials  of  the  ancient 
crystalline  schists  were  accumulated,  it  cannot  be  doubted  that 
the  chemical  processes  which  generated  silicates  were  much 
more  active  than  in  more  recent  times.  The  heat  of  the  earth's 
crust  was  probably  then  far  greater  than  at  present,  while  a 
high  temperature  prevailed  at  comparatively  small  depths,  and 
thermal  waters  abounded.  A  denser  atmosphere,  charged  with 
carbonic-acid  gas,  must  also  have  contributed  to  maintain,  at 
the  earth's  surface,  a  greater  degree  of  heat,  though  one  not 
incompatible  with  the  existence  of  organic  life.  (Ante,  page 
46.)  These  conditions  must  have  favored  many  chemical 
processes,  which,  in  later  times,  have  nearly  ceased  to  operate. 
Hence  we  find  that  subsequently  to  the  eozoic  times,  silicated 
rocks  of  clearly  marked  chemical  origin  are  comparatively 
rare.  In  the  mechanical  sediments  of  later  periods  certain 
crystalline  minerals  may  be  developed  by  a  process  of  mo- 
lecular rearrangement,  —  di agenesis.  These  are,  in  the  feld- 
spathic  and  aluminous  sediments,  orthoclase,  muscovite,  garnet, 
staurolite,  cyanite,  and  chiastolite,  and  in  the  more  basic  sedi- 
ments, hornblendic  minerals.  It  is  possible  that  these  latter 
and  similar  silicates  may  sometimes  be  generated  by  reactions 
between  silica  on  the  one  hand  and  carbonates  and  oxides  on 
the  other,  as  already  pointed  out  in  some  cases  of  local  altera- 
tion. Such  a  case  may  apply  to  more  or  less  hornblendic 
gneisses,  for  example,  but  no  sediments,  not  of  direct  chemical 
origin,  are  pure  enough  to  have  given  rise  to  the  great  beds  of 
serpentine,  pyroxene,  steatite,  labradorite,  etc.,  which  abound 
in  the  ancient  crystalline  schists.  Thus,  while  the  materials 

•were  once  pastes,  magmas  or  muds,  and  so  were  the  primitive  rocks  at  the 
time  of  their  origin,  but  during  these  first  ages  of  the  earth  the  consolidating 
and  crystallizing  forces  (differing  in  degree  only  from  those  of  the  present 
time,  and  aided  by  a  higher  temperature)  allowed  the  magma  to  assume  the 
form  of  mineral  species,  more  or  less  distinct.  If  we  choose  to  call  this 
change  metamorphism,  then  the  rocks  thus  formed  are  metarnorphic;  but  so 
also  are  the  limestones  of  later  periods.  The  primitive  rocks  originated  by 
way  of  sedimentation,  the  one  after  the  other,  constituting  distinct  forma- 
tions, and  there  are  no  eruptive  gneisses."  See,  in  this  connection,  the  Intro- 
duction to  Essay  III.  of  the  present  volume,  and  the  statements  of  Favre  in 
the  Appendix  to  Essay  XIV.] 


XIII.]  ORIGIN   OF  CRYSTALLINE  ROCKS.  307 

for  producing,  by  diagenesis,  the  aluminous  silicates  just  men- 
tioned are  to  be  met  with  in  the  mud  and  clay-rocks  of  all 
ages,  the  chemically  formed  silicates,  capable  of  crystallizing 
into  pyroxene,  talc,  serpentine,  etc.,  have  only  been  formed 
under  special  conditions.  [While  the  generation  of  various 
crystalline  silicated  minerals  in  rocks  since  the  Eozoic  age  is 
theoretically  not  impossible,  the  accumulation  of  evidence  goes 
to  show  that  although  such  changes  have  taken  place  locally  in 
the  proximity  of  eruptive  rocks,  and  by  the  invasion  of  thermal 
waters,  there  has  been  no  wide-spread  alteration  or  regional 
metamorphism,  as  it  has  been  called,  of  these  more  recent 
sedimentary  deposits.] 

The  same  reasoning  which  led  me  to  maintain  the  theory  of 
an  original  formation  of  the  mineral  silicates  of  the  crystalline 
schists,  induced  me  to  question  the  received  notion  of  the  epi- 
genic  origin  of  gypsums  and  magnesian  limestones  or  dolomites. 
The  interstratification  of  dolomites  and  pure  limestones,  and 
the  enclosure  of  pebbles  of  the  latter  in  a  paste  of  crystalline 
dolomite,  are  of  themselves  sufficient  to  show  that  in  these 
cases,  at  least,  dolomites  have  not  been  formed  by  the  altera- 
tion of  pure  limestones.  The  first  results  of  a  very  long  series 
of  experiments  and  inquiries  into  the  history  of  gypsum  were 
published  by  me  in  1859,  and  further  researches,  reiterating 
and  confirming  my  previous  conclusions,  appeared  in  1866. 
(Ante,  page  80.)  In  these  two  papers  it  will,  I  think,  be 
found  that  the  following  facts  in  the  history  of  dolomite  are 
established  :  namely,  first,  its  origin  in  nature  by  direct  sedi- 
mentation, and  not  by  the  alteration  of  non-magnesian  lime- 
stones ;  second,  its  artificial  production  by  the  direct  union  of 
carbonate  of  lime  and  hydrous  carbonate  of  magnesia,  at  a  gen- 
tle heat,  in  the  presence  of  water.  As  to  the  sources  of  the 
hydrous  magnesian  carbonate,  I  have  endeavored  to  show  that 
it  is  formed  from  the  magnesian  chloride  or  sulphate  of  the  sea 
or  other  saline  waters  in  two  ways  :  first,  by  the  action  of  the 
bicarbonate  of  soda  found  in  many  natural  waters.;  this,  after 
converting  all  soluble  lime-salts  into  insoluble  carbonate,  forms 
a  comparatively  soluble  bicarbonate  of  magnesia,  from  which  a 


308  ORIGIN   OF   CRYSTALLINE  ROCKS.  [XIII. 

hydrous  carbonate  slowly  separates ;  second,  by  the  action  of 
bicarbonate  of  lime  in  solution,  which,  with  sulphate  of  mag- 
nesia, gives  rise  to  gypsum  ;  this  first  crystallizes  out,  leaving 
behind  a  much  more  soluble  bicarbonate  of  magnesia,  which 
deposits  the  hydrous  carbonate  in  its  turn.  In  this  way,  for 
the  first  time,  in  1859,  the  origin  of  gypsums  and  their  inti- 
mate relation  with  magnesian  limestones  were  explained.* 

It  was,  moreover,  shown  that,  to  the  perfect  operation  of  this 
reaction,  an  excess  of  carbonic  acid  in  the  solution  during  the 
evaporation  was  necessary  to  prevent  the  decomposing  action 
of  the  hydrous  mono-carbonate  of  magnesia  upon  the  already 
formed  gypsum.  Having  found  that  a  prolonged  exposure  to 
the  air,  by  permitting  the  loss  of  carbonic  acid,  partially  inter- 
fered with  the  process,  I  was  led  to  repeat  the  experiment  in  a 
confined  atmosphere,  charged  with  carbonic  acid,  but  rendered 
drying  by  the  presence  of  a  layer  of  desiccated  chloride  of  cal- 
cium. As  had  been  foreseen,  the  process  under  these  conditions 
proceeded  uninterruptedly,  pure  gypsum  first  crystallizing  out 
from  the  liquid,  and,  subsequently,  the  hydrous  magnesian 
carbonate,  t  This  experiment  is  instructive,  as  showing  the 
results  which  must  have  attended  this  process  in  past  ages, 
when  the  quantity  of  carbonic  acid  in  the  atmosphere  greatly 
exceeded  its  present  amount.  (Ante,  pages  43,  *47,  and  91.) 

As  regards  the  hypotheses  put  forward  to  explain  the  supposed 
dolomitization  of  previously  formed  limestones  by  an  epigenic 
process,  I  may  remark  .that  I  repeated  very  many  times,  under 
varying  conditions,  the  often-cited  experiment  of  Yon  Morlot, 
who  claimed  to  have  generated  dolomite  by  the  action  of  sul- 
phate of  magnesia  on  carbonate  of  lime,  in  the  presence  of  water 
at  a  somewhat  elevated  temperature  under  pressure.  I  showed 
that  what  he  regarded  as  dolomite  was  not  such,  but  an  admixt- 
ure of  carbonate  of  lime  with  anhydrous  and  sparingly  soluble 
carbonate  of  magnesia  ;  the  conditions  in  which  the  carbonate 
of  magnesia  is  liberated  in  this  reaction  not  being  favorable  to 
its  union  with  the  carbonate  of  lime  to  form  the  double  salt 

*  See  the  recent  conclusions  of  Ramsay,  noticed  ante,  page  92. 
t  Canadian  Naturalist,  new  series. 


XIII. ]  ORIGIN   OF  CRYSTALLINE  ROCKS.  309 

which  constitutes  dolomite.  The  experiment  of  Marignac,  who 
thought  to  form  dolomite  by  substituting  a  solution  of  chloride 
of  magnesium  for  the  sulphate,  I  found  to  yield  similar  results, 
the  greater  part  of  the  magnesiau  carbonate  produced  passing  at 
once  into  the  insoluble  condition,  without  combining  with  the 
excess  of  carbonate  of  lime  present.  The  process  for  the  pro- 
duction of  the  double  carbonate  described  by  Charles  Deville, 
namely,  the  action  of  vapors  of  anhydrous  magnesian  chloride 
on  heated  carbonate  of  lime,  in  accordance  with  Von  Buch's 
strange  theory  of  dolomitization,  I  have  not  thought  necessary 
to  submit  to  the  test  of  experiment,  since  the  conditions  re- 
quired are  scarcely  conceivable  in  nature.  Multiplied  geognos- 
tical  observations  show  that  the  notion  of  the  epigenic  pro- 
duction, of  dolomite  from  limestone  is  untenable,  although  its 
re-solution  and  deposition  in  veins,  cavities,  or  pores  in  other 
rocks  is  a  phenomenon  of  frequent  occurrence. 

The  dolomites  or  magnesian  limestones  may  be  conveniently 
considered  in  two  classes  :  first,  those  which  are  found  with 
gypsums  at  various  geological  horizons  ;  and,  second,  the  more 
abundant  and  widely  distributed  rocks  of  the  same  kind,  which 
are  not  associated  with  deposits  of  gypsum.  The  production 
of  the  first  class  is  dependent  upon  the  decomposition  of  sul- 
phate of  magnesia  by  solutions  of  bicarbonate  of  lime,  while 
those  of  the  second  class  owe  their  origin  to  the  decomposition 
of  magnesian  chloride  or  sulphate  by  solutions  of  alkaline  bi- 
carbonates.  In  both  cases,  however,  the  bicarbonate  of  mag- 
nesia, which  the  carbonated  waters  generally  contain,  contributes 
a  more  or  less  important  part  to  the  generation  of  the  magnesian 
sediments.  The  carbonated  alkaline  waters  of  deep-seated 
springs  often  contain,  as  is  well  known,  besides  the  bicarbonates 
of  soda,  lime  and  magnesia,  compounds  of  iron,  manganese, 
and  many  of  the  rarer  metals  in  solution  ;  and  thus  the  metal- 
liferous character  of  many  of  the  dolomites  of  the  second  class 
is  explained.  The  simultaneous  occurrence  of  alkaline  silicates 
in  such  mineral  waters  would  give  rise,  as  already  pointed  out, 
to  the  production  of  insoluble  silicates  of  magnesia,  and  thus 
the  frequent  association  of  such  silicates  with  dolomites  and 


310  ORIGIN   OF  CRYSTALLINE  ROCKS.  [XIII. 

magnesian  carbonates  in  the  crystalline  schists  is  explained,  as 
marking  portions  of  one  continuous  process.  The  formation  of 
these  mineral  waters  depends  upon  the  decomposition  of  feld- 
spathic  rocks  by  subterranean  or  sub-aerial  processes,  which  were 
doubtless  more  active  in  former  ages  than  in  our  own.  The 
subsequent  action  upon  magnesian  waters  of  these  bicarbonated 
solutions,  whether  alkaline  or  not,  is  dependent  upon  climatic 
conditions ;  since,  in  a  region  where  the  rain-fall  is  abundant, 
such  waters  would  find  their  way  down  the  river-courses  to  the 
open  sea,  where  the  excess  of  dissolved  sulphate  of  lime  would 
prevent  the  deposition  of  magnesian  carbonate.  It  is  in  dry 
and  desert  regions,  with  closed  lake  or  sea  basins,  that  we  must 
seek  for  the  production  of  magnesian  carbonates ;  and  I  have 
argued  from  these  considerations  that  much  of  northeastern 
America,  including  the  present  basins  of  the  Upper  Mississippi, 
Ohio,  and  St.  Lawrence,  must,  during  long  intervals  in  the 
palaeozoic  period,  have  had  a  climate  of  excessive  dryness,  and 
a  surface  marked  by  shallow  enclosed  basins,  as  is  shown  by  the 
widely  spread  magnesian  limestones,  and  by  the  existence  of 
gypsum  and  rock-salt  at  more  than  one  geological  horizon  within 
that  area.*  (Ante,  page  76.)  The  occurrence  of  serpentine  and 
diallage  at  Syracuse,  New  York,  offers  a  curious  example  of  the 
local  development  of  crystalline  magnesian  silicates  in  Silurian 
dolomitic  strata,  under  conditions  which  are  imperfectly  known, 
and,  in  the  present  state  of  the  locality,  cannot  be  studied,  t 

Since  the  uncombined  and  hydrated  magnesian  mono-carbon- 
ate is  at  once  decomposed  by  sulphate  or  chloride  of  calcium,  it 
follows  that  the  whole  of  these  lime-salts  in  a  sea-basin  must  be 
converted  into  carbonates  before  the  production  of  carbonated 
magnesian  sediments  can  begin.  The  carbonate  of  lime  formed 
by  the  action  of  carbonates  of  magnesia  and  soda  remains  at 
first  dissolved,  either  as  carbonate  (ante,  page  140)  or  as  bicar- 
bonate, and  is  only  separated  in  a  solid  form,  when  in  excess, 

*  Geology  of  Southwestern  Ontario,  American  Journal  of  Science  (2), 
XLVII.  355. 

t  Geology  of  the  Third  District  of  New  York,  108-110;  and  Hunt  on 
Ophiolites,  American  Journal  of  Science  (2),  XXVI.  236. 


XIIL]  ORIGIN  OF  CRYSTALLINE  ROCKS.  311 

or  when  required  for  the  needs  of  living  plants  or  animals, 
which  are  dependent  for  their  supply  of  calcareous  matter  on 
the  carbonate  of  lime  produced,  in  part  by  the  process  just  de- 
scribed, and  in  part  by  the  action  of  carbonic  acid  on  insoluble 
lime-compounds  of  the  earth's  solid  crust.  So  many  limestones 
are  made  up  of  calcareous  organic  remains,  that  a  notion  exists 
among  many  writers  on  geology  that  all  limestones  are,  in  some 
way,  of  organic  origin.  At  the  bottom  of  this  lies  the  idea  of 
an  analogy  between  the  chemical  relations  of  vegetable  and 
animal  life.  As  plants  give  rise  to  beds  of  coal,  so  animals  are 
supposed  to  produce  limestones.  In  fact,  however,  the  syn- 
thetic process  by  which  the  growing  plant,  from  the  elements 
of  water,  carbonic  acid,  and  ammonia,  generates  hydrocarbona- 
ceous  and  azotized  matters,  has  no  analogy  with  the  assimilative 
process  by  which  the  growing  animal  appropriates  alike  these 
organic  matters  and  the  carbonate  and  phosphate  of  lime. 
Without  the  plant,  the  synthesis  of  the  hydrocarbons  would 
not  take  place  ;  while,  independently  of  the  existence  of  coral 
or  mollusk,  the  carbonate  of  lime  would  still  be  generated  by 
chemical  reactions,  and  would  accumulate  in  the  waters  until, 
these  being  saturated,  its  excess  would  be  deposited  as  gypsum 
or  rock-salt  are  deposited.  Hence,  in  such  waters,  where,  from 
any  causes,  life  is  excluded,  accumulations  of  pure  carbonate 
of  lime  may  be  formed.  In  1861  I  called  attention  to  the 
white  marbles  of  Vermont,  which  occur  intercalated  among 
impure  and  fossiliferous  beds,  as  apparently  examples  of  such 
a  process.* 

It  is  by  a  fallacy  similar  to  that  which  prevails  as  to  the  or- 
ganic origin  of  limestones,  that  Daubeny  and  Murchison  were 
led  to  appeal  to  the  absence  of  phosphates  from  certain  old 
strata,  as  evidence  of  the  absence  of  organic  life  at  the  time  of 
their  accumulation,  f  Phosphates,  like  silica  and  iron-oxide, 
were  doubtless  constituents  of  the  primitive  earth's  crust,  and 
the  production  of  apatite  crystals  in  granitic  veins  or  in  crys- 
talline schists  is  a  process  as  independent  of  life  as  the  forma- 

*  American  Journal  of  Science  (2),  XXXI.  402. 
t  Siluria,  4th  ed.,  pp.  28  and  537. 


312  ORIGIN   OF  CRYSTALLINE  ROCKS.  [XIII. 

tion  of  crystals  of  quartz  or  of  hematite.  Growing  plants,  it 
is  true,  take  up  from  the  soil  or  the  waters  dissolved  phosphates, 
which  pass  into  the  skeletons  of  animals,  —  a  process  which 
has  "been  active  from  very  remote  periods.  I  showed,  in  1854, 
that  the  shells  of  Lingula  and  Orbicula,  both  those  from  the 
base  of  the  palaeozoic  rocks  and  those  of  the  present  time,  have 
(like  Conularia  and  Serpulites)  a  chemical  composition  similar 
to  the  skeletons  of  vertebrate  animals.*  The  relations  of  both 
carbonate  and  phosphate  of  lime  to  organized  beings  are  similar 
to  those  of  silica,  which,  like  them,  is  held  in  watery  solution, 
and  by  processes  independent  of  life,  is  deposited  both  in 
amorphous  and  crystalline  forms,  but  in  certain  cases  is  appro- 
priated by  diatoms  and  sponges,  and  made  to  assume  organized 
shapes.  In  a  word,  the  assimilation  of  silica,  like  that  of  phos- 
phate and  carbonate  of  lime,  is  a  purely  secondary  and  acci- 
dental process  ;  and  where  life  is  absent,  all  of  these  substances 
are  deposited  in  mineral  and  inorganic  forms. 

*  American  Journal  of  Science  (2),  XVII.  236. 


XIII.]  ORIGIN   OF  CRYSTALLINE  ROCKS.  313 


APPENDIX. 
• 

REPLY   TO   MR.    DANA'S   CRITICISMS. 

IN  the  American  Journal  of  Science  for  February,  1872,  Professor 
Dana  has  criticised  certain  points  in  my  address,  On  the  Geognosy 
of  the  Appalachians  and  the  Origin  of  Crystalline  Rocks,  given  in 
August,  -1871,  at  Indianapolis,  before  the  American  Association  for 
the  Advancement  of  Science.  1  am  charged  by  him  with  rejecting, 
for  many  mineral  silicates,  the  view  that  they  are  pseudomorphs ; 
that  is  to  say,  crystals  chemically  altered  without  loss  of  external 
form.  I  have  denied  that  crystals  of  serpentine  having  the  shape 
of  chrysolite,  pyroxene,  dolomite,  etc.,  and  crystals  of  pinite  having 
the  shapes  of  nepheline  or  scapolite,  are  results  of  a  chemical 
change  of  these  species,  noth withstanding  this  view  is  now  held 
by  most  mineralogists,  on  the  grounds  of  similarities  of  geometrical 
form  and  the  existence  of  what  are  regarded  as  intermediate  stages  in 
the  process  of  transmutation  ;  and  I  have  maintained  another  and 
a  very  different  view,  which,  in  my  opinion,  is  more  rational.  Until 
we  can  watch  the  transmutation  of  one  of  these  species  into  another, 
the  argument  from  supposed  intermediate  forms  is  worth  no  more  in 
the  mineral  than  in  the  organic  world ;  the  reasoning  of  the  trans- 
mutationists,  in  the  one  case  and  the  other,  resting  upon  somewhat 
similar  considerations.  In  either  case  we  may  say,  with  Professor 
Warrington  Smyth,  that  in  these  intermediate  forms  "  lie  the  ma- 
terials for  a  history n  ;  while  we  venture,  with  him,  to  express  a 
doubt  whether,  from  a  series  of  specimens  supposed  to  show  a 
transition  from  chrysolite  to  serpentine,  or  from  hornblende  to 
chlorite,  "  we  are  obliged  to  conclude  that  there  has  been,  histori- 
cally speaking,  an  actual  transition  from  the  one  to  the  other."  (See 
his  anniversary  address,  as  President  of  the  Geological  Society  of 
London,  in  1867.) 

Professor  Dana  says  that  Scheerer  is  the  only  one  who  shares  my 
peculiar  views  on  this  question.  I  have,  however,  asserted  in  my 
address  that  Delesse  has  maintained  the  views  of  Scheerer  and 
myself,  as  opposed  to  the  popular  doctrine  of  epigenesis,  and  shall 
endeavor  to  make  good  my  assertion.  In  his  essay  on  Pseudo- 
morphs, published  in  1859  (Ann.  des  Mines  (5),  XVI.  317  -  392), 
14 


314  ORIGIN   OF   CRYSTALLINE   ROCKS.  [XIII. 

Delesse  begins  his  argument  by  remarking  that  since,  in  some  cases, 
a  mineral  is  found  to  be  surrounded  by  another  clearly  resulting 
from  its  alteration  (as,  for  example,  anhydrite  by  gypsum),  certain 
mineralogists  have  supposed  that  wherever  one  mineral  encloses 
another  there  has  been  epigenesis  or  pseudomorphous  alteration. 
Such,  he  says,  may  sometimes  be  the  case,  but  it  is  easy  to  see  that 
it  is  not  so  habitually.  A  crystallized  mineral  species  frequently 
includes  a  large  and  even  a  predominating  portion  of  another,  and 
the  combination  is  then  considered  by  many  as  an  example  of 
partial  pseudomorphous  alteration.  In  such  instances,  remarks 
Delesse,  the  question  arises  whether  we  have  to  do  with  the 
results  of  envelopment  or  of  chemical  alteration  ;  to  resolve  which 
it  becomes  necessary  to  study  carefully  the  problem  of  envelopment. 
He  then  proceeds  to  show  that  the  enveloped  substance  is,  in  some 
cases,  crystalline  (and  arranged  either  symmetrically  or  asymmetri- 
cally with  regard  to  the  enveloping  mass) ;  while  in  other  cases  it  is 
amorphous,  and  enclosed  like  the  sand- grains  which  predominate  in 
the  calcite  crystals  of  Fontainebleau.  The  difficulty  in  deciding 
whether  we  have  to  do  with  envelopment  or  with  epigenesis  increases 
when  the  enveloped  mineral  becomes  so  abundant  as  to  obscure  the 
enveloping  species,  or  when  it  becomes  mixed  with  it  in  so  intimate 
a  manner  as  to  seem  one  \vith  the  latter  (se  fondre  insensiblement  avec 
lui).  The  proportions  of  the  enveloped  and  the  enveloping  mineral, 
we  are  told,  may  so  far  vary  that  the  one  or  the  other  is  no  longer 
recognizable.  "  As  the  forces  which  determine  crystallization  have 
a  great  energy,  the  enveloping  mineral  is  sometimes  found  in  so 
small  a  quantity  as  to  be  entirely  masked  by  the  enveloping  species." 
"  When  minerals  have  crystallized  simultaneously,  they  have  been 
able  to  become  associated  with  each  other  and  to  envelop  each  other 
in  all  proportions  "  (loc.  cit.,  pages  338,  339,  341,  353). 

Our  author  then  proceeds  to  tell  us  that,  having  carefully  studied 
in  numerous  specimens  the  supposed  mica-pseudomorphs  of  iolite, 
andalusite,  cyanite,  pyroxene,  hornblende,  etc.,  he  regards  them  as, 
in  all  cases,  examples  of  envelopment,  and  expresses  the  opinion 
that  we  must  omit  from  our  lists  a  great  number  of  the  so-called 
pseudomorphous  minerals,  especially  among  the  silicates.  The  final 
result  of  the  process  of  envelopment  is,  according  to  Delesse,  this, 
—  to  give  rise  to  mixed  mineral  aggregates,  owing  their  external 
forms  to  the  crystallizing  energy  of  one  of  the  constituents,  which 
may  be  present  in  so  small  a  quantity  as  to  be  completely  obscured 
by  the  other  matter  present.  From  this  condition  of  things  result 


XIIL]  ORIGIN   OF   CRYSTALLINE  ROCKS.  315 

crystalline  forms  which,  though  totally  different  in  their  origin  from 
the  products  of  chemical  alteration  or  substitution,  are  emphatically 
pseudomorphs. 

From  this  process  of  mechanical  and  more  or  less  heterogeneous 
envelopment,  Delesse  next  proceeds  to  consider  the  crystallizing 
together  of  isomorphous  or  homoeomorphous  species,  in  relation  to 
the  generally  received  notion  of  epigenic  pseudomorphism.  He 
declares  that  "isomorphism  explains  very  well  facts  which  are 
often  attributed  to  pseudomorphism,"  and  that  many  "  minerals 
which  are  still  considered  pseudomorphs  are  in  reality  examples  of 
isomorphism"  (pages  364,  365).  Referring  to  the  well-known  in- 
vestigations of  Mitscherlich  upon  the  crystallizing  together,  in  all 
proportions,  of  isomorphous  species,  and  of  the  symmetrical  crys- 
tallization of  one  salt  around  a  nucleus  of  another  isomorphous 
with  it,  Delesse  suggests  that  the  different  forms  and  varieties  of 
hornblendic  and  pyroxenic  minerals  afford  many  examples  of  the 
kind.  He  then  adds,  "  If,  as  Scheerer  has  remarked,  water  plays  in 
silicates  the  part  of  a  base,  anhydrous  silicates  may  crystallize  at 
the  same  time  with  hydrated  silicates,  and,  moreover,  be  isomor- 
phous with  them."  In  this  way,  he  suggests,  we  may  explain  by 
isomorphism  or  homoeomorphism,  the  association  with  pyroxene 
of  the  hydrous  species,  schiller-spar,  as  well  as  that  "  of  various 
anhydrous  and  hydrated  minerals"  (pages  357,  358). 

In  further  illustration  of  the  words  just  quoted  from  Delesse,  we 
may  cite  from  Scheerer,  as  examples  of  what  he  called  polymeric 
isomorphism,  the  association  (in  the  same  crystals)  of  iolite  and 
aspasiolite,  and  of  chrysolite  and  serpentine.  If  these  and  similar 
species  crystallize  together  because  they  are  isomorphous,  it  is 
evident  that  they  may  each  crystallize  separately ;  and  thus  the 
crystals  of  serpentine  with  the  form  of  chrysolite,  and  those  of 
aspasiolite  and  other  so-called  hydrous  iolites,  may  be  regarded  as 
examples,  not  of  epigenesis,  but  of  isomorphism. 

We  have  thus  endeavored  to  set  forth,  chiefly  in  his  own  words, 
the  views  enunciated  in  1859  by  Delesse,  according  to  whom  the 
phenomena  of  so-called  pseudomorphism  among  mineral  silicates 
are  to  be  explained,  for  the  most  part,  not  by  chemical  alterations 
of  pre-existing  species,  but  by  envelopment  and  by  isomorphism. 
That  the  above  are  really  his  views,  and  are,  moreover,  regarded  by 
himself  as  contrary  to  those  of  the  school  which  I  oppose,  Delesse 
does  not  permit  us  to  doubt ;  for,  after  having  set  them  forth  as  his 
own  (aprh  avoir  exposJ  notre  manibre  dt  voir),  he  says,  "  We  hasten 


316  ORIGIN   OF   CRYSTALLINE  ROCKS.  [XIII. 

to  add  that  these  facts  may  also  be  explained  in  a  manner  altogether 
different  (peuvent  aussi  ^interpreter  d'une  maniere  toute  difftfrente)  ; 
and  some  savans  of  Germany,  notably  G.  Rose,  Haidinger,  Blum, 
G.  Bischof,  and  Rammelsberg,  have  sought  their  explanation  in 
pseudomorphism.  Their  example  has  been  followed  by  most  min- 
eralogists, etc."  (pages  358,  359). 

That  the  "  pseudomorphism "  of  the  authors  just  named  is 
chemical  altera.ion  or  epigenesis,  it  is  not  necessary  to  remind  the 
reader,  who  will  now  be  able  to  judge  whether  it  is  Professor  Dana 
or  myself  who  has  misrepresented  or  misunderstood  Delesse.  Let 
us,  however,  add  that  the  long  and  somewhat  diffuse  memoir  of  the 
latter,  from  which  we  have  quoted,  is  wanting  in  unity  of  plan  and 
purpose,  and  that  parts  of  it,  if  we  may  hazard  a  conjecture,  seem 
to  have  been  written  while  he  still  inclined  to  the  views  of  the 
opposite  school.  From  the  table  of  pseudomorphs  which  he  has 
given,  and  from  many  passages  in  the  text,  it  might  be  inferred  that 
he  then  held  the  notions  of  Rose,  Haidinger,  etc.,  which  he  else- 
where, in  the  same  paper,  speaks  of  as  being  entirely  different  from 
his  own.  The  views  of  Delesse,  about  this  time,  underwent  a  great 
change,  which  has  a  historic  importance  in  connection  with  those 
which  I  advocate.  When,  in  1857  and  1858,  he  published  the  first 
and  second  parts  of  his  admirable  series  of  studies  on  metamor- 
phism,  Delesse  held,  in  common  with  nearly  every  geologist  of  the 
time,  to  the  eruptive  origin  of  serpentine  and  the  related  magnesian 
rocks.  Serpentine  was  then  classed  by  him  with  other  "  trappean 
rocks "  ;  and  he  elsewhere  asserted  that  "  granitic  and  trappean 
rocks"  undergo  in  certain  cases  a  change  near  their  contact  with 
the  enclosing  rock,  by  which  they  lose  silica,  alumina,  and  alkalies, 
and  acquire  magnesia  and  water,  being  thus  changed  into  a  mag- 
nesian silicate,  which  may  take  the  form  of  saponite,  serpentine, 
talc,  or  chlorite  (Ann.  des  Mines  (5),  XII.  509  ;  XIII.  393,  415).  It 
would  be  difficult  to  state  more  distinctly  the  view,  which  he  then 
held,  of  the  origin  of  these  magnesian  rocks  and  minerals  by  the 
chemical  alteration  of  plutonic  (granitic  and  trappean)  rocks.  This 
was  in  1858,  and  in  1859  appeared  the  memoir  on  pseudomorphs, 
already  noticed,  in  which,  in  place  of  the  theory  of  epigenic  pseudo- 
morphism, or  chemical  alteration  of  various  mineral  silicates,  taught 
by  the  German  school,  he  brought  forward,  in  explanation  of  the 
facts  upon  which  this  was  based,  another  theory,  which  was  only  an 
extension  of  that  already  maintained  by  Scheerer  and  myself. 

It  was  not  until  1861  that  Delesse  published  the  last  part  of  his 


XIIL]  ORIGIN   OF   CRYSTALLINE  ROCKS.  317 

studies  on  metamorphism,  which  appeared  in  the  Memoirs  of  the 
Academy  of  Sciences  of  France  (Vol.  XVII.)  ;  and  in  it  we  find  that, 
consistently  with  the  new  views  adopted  by  him  in  1859,  the  old 
doctrine  of  the  epigenic  origin  of  serpentine  and  the  related  mag- 
nesian  rocks  from  the  alteration  of  plutonic  rocks  is  abandoned. 
In  its  stead,  it  is  here  suggested  by  Delesse  that  all  these  magnesian 
rocks  result  from  the  crystallization  of  the  sepiolites  or  so-called 
magnesian  clays,  which  are  frequent  in  many  sedimentary  deposits. 
These,  according  to  him,  by  a  molecular  rearrangement  of  their 
elements,  may  give  rise  to  serpentine,  talc,  chlorite,  and  their 
various  associated  and  related  minerals.  The  rocks  thus  generated 
are  still  declared  to  pass  insensibly  into  plutonic  rocks  ;  but,  instead 
of  maintaining,  as  in  1858,  that  they  are  derived  from  the  latter, 
Delesse,  in  1861,  asserts,  on  the  contrary,  that  "the  plutonic  rocks 
are  formed  from  the  metauiorphic  rocks,  and  represent  the  maximum 
of  intensity,  or  extreme  limit  of  metamorphism." 

This  recognition  of  the  notion  that  the  great  masses  of  serpen- 
tine, with  their  constantly  associated  hornblendic,  talcose  and 
chloritic  rocks,  have  been  directly  formed  from  the  molecular  re- 
arrangement or  diagenesis  of  aqueous  magnesian  sediments,  and  not 
from  the  chemical  alteration  or  epigenesis  of  erupted  plutonic 
masses,  marks  a  complete  revolution  in  our  views  of  the  history  of 
the  crystalline  rocks.  The  new  doctrine  did  not,  however,  originate 
with  Delesse,  but  was  previously  put  forward  by  myself  in  a  paper, 
On  some  Points  of  Chemical  Geology,  read  before  the  Geological 
Society  of  London  in  January,  1859,  appearing  in  abstract  in  the 
Philosophical  Magazine  for  February,  and  published  at  length  in 
the  Geological  Journal  for  November,  in  the  same  year.  I  there 
maintained  that  serpentines  were  "  undoubtedly  indigenous  rocks, 
resulting  from  the  alteration  of  silico-magnesian  sediments  "  ;  and 
moreover  asserted  that  the  final  result  of  heat,  aided  by  water,  on 
such  rocks,  would  be  their  softening,  and,  in  certain  cases,  their  ex- 
travasation as  plutonic  rocks  ;  which  were  regarded  "  as,  in  all 
cases,  altered  and  displaced  sediments."  When  this  paper  was 
written,  in  1858,  I  still  supposed  that  the  reactions  between  the 
elements  in  beds  of  silicious  magnesian  carbonates  (which,  I  had 
shown,  may  give  rise  to  certain  magnesian  silicates  in  immediate 
proximity  to  eruptive  rocks)  might  serve  to  explain  the  origin  of 
great  areas  of  serpentine  and  related  crystalline  magnesian  sili- 
cates ;  bnt  my  studies  of  the  silicates  deposited  during  the  evapora- 
tion of  natural  waters,  and  of  the  magnesian  sediments  of  the  Paris 


318  ORIGIN   OF   CRYSTALLINE   ROCKS.  [XIII. 

basin,  soon  led  me  to  seek  the  origin  of  these  rocks  in  the  alteration 
of  previously  formed  uncrystalline  magnesian  silicates.  This  view 
was  set  forth  by  me  in  the  American  Journal  of  Science  for  March, 
1860  ((2),  XXIX.  284).  and  more  fully  in  the  Canadian  Naturalist 
for  June,  1860  (also  in  the  American  Journal  (2),  XXXII.  286), 
where  it  was  pointed  out  that  steatite,  chlorite  and  serpentine  were 
probably  derived  from  sediments  similar  to  the  magnesian  silicates 
found  among  the  tertiary  beds  in  the  vicinity  of  Paris,  the  so-called 
magnesian  clays. 

We  have  seen  that  these  various  novel  views,  put  forth  by  me  in 
1859  and  1860,  though  totally  different  from  those  taught  by  De- 
lesse  in  1858,  were  integrally  adopted  by  him  in  1861."  These  dates 
are  circumstantially  given  in  my  address  of  last  year,  and  yet  Pro- 
fessor Dana,  in  his  review  of  it,  charges  me  with  "  following  nearly 
Delesse  "  as  to  the  origin  of  serpentine.  He  also  asserts  that  I 
"  make  Delesse  the  author  of  the  theory  of  envelopment,"  when  I 
have  there  declared  that  the  view  of  Delesse  —  "  that  the  so-called 
cases  of  pseudomorphism,  on  which  the  theory  of  metamorphism  by 
alteration  has  been  built,  are,  for  the  most  part,  examples  of  associa- 
tion and  envelopment,  and  the  result  of  a  contemporaneous  and 
original  crystallization  —  is  identical  with  the  view  suggested  by 
Scheerer  in  1846,  and  generalized  by  myself,  when,  in  1853,  I 
sought  to  explain  the  phenomena  in  question  by  the  association  and 
crystallizing  together  of  homologous  and  isomorphous  species."  To 
Delesse,  therefore,  belongs  the  merit,  not  of  having  suggested  the 
notion  of  envelopment  in  this  connection,  but  of  having  pointed  out 
the  bearing  of  the  envelopment  of  heteromorphous  and  amorphous 
species  on  the  question  before  us. 

Professor  Dana  moreover  asserts  that,  while  Scheerer  is  the  only 
one  who  maintains  similar  views  to  myself,  I,  in  common  with 
all  other  chemists,  reject  the  chemical  speculations  which  lie  at  the 
base  of  his  views.  On  the  contrary,  unlike  most  chemists,  who 
have  failed  to  see  the  great  principle  which  underlies  Scheerer's 
doctrine  of  polymeric  isomorphism,  I  have  maintained  (American 
Journal  of  Science  (2),  XV.  230 ;  XVI.  218)  that  it  enters  into  a 
general  law,  in  accordance  with  which  bodies  whose  formulas  differ 
by  nM2O2  or  nH202  may  (like  those  differing  by  nH2C2)  have  rela- 
tions of  homology,  and  moreover  be  isomorphous.  (See,  further, 
Paper  XVII.  of  the  present  volume.)  The  existence  of  these  same 
relations  was  further  maintained  and  exemplified  in  a  paper  on 
Atomic  Volumes,  read  by  me  before  the  French  Academy  of 


XIIL]  OBIGIN   OF  CRYSTALLINE  ROCKS.  319 

Sciences  and  published  in  the  Comptes  Rendus  of  July  9,  1855. 
This  doctrine,  which  I  have  never  repudiated,  is  reiterated  in  my 
address  last  year  (ante,  page  291),  and  declared  to  include  the  poly- 
meric isomorphism  of  Scheerer. 

Professor  Dana  next  says  that,  in  asserting  that  "  the  doctrine  of 
pseudomorphism  by  alteration,  as  taught  by  G.  Rose,  Haidinger, 
Blum,  Volger,  Rammelsberg,  Dana,  Bischof,  and  many  others,  leads 
them  ....  to  maintain  the  possibility  of  converting  almost  any 
silicate  into  any  other,"  I  have  "  grossly  misrepresented  the  views 
of  at  least  Rose,  Haidinger,  Blum,  Rammelsberg,  and  Dana "  ;  and 
that  I  "  complete  the  caricature "  by  this  sentence,  to  be  found  in 
my  address  :  "  In  this  way  we  are  led  from  gneiss  or  granite  to 
limestone,  from  limestone  to  dolomite,  and  from  dolomite  to  ser- 
pentine ;  or  more  directly  from  granite,  granulite,  or  diorite,  to  ser- 
pentine at  once,  without  passing  through  the  intermediate  stages  of 
limestone  and  dolomite  "  ;  —  "  part  of  which  transformations,"  says 
Professor  Dana,  "  I,  for  one,  had  never  conceived  ;  and  Rose,  Hai- 
dinger,  Rammelsberg,  and  probably  Blum,  and  the  'many  others,' 
would  repudiate  them  as  strongly  as  myself."  The  "  many  others," 
as  he  rightly  remarks,  are  "other  writers  on  pseudomorphism," 
among  whom  it  would  be  unjust  not  to  name  their  progenitor, 
Breithaupt,  Von  Rath,  and  Midler,  at  the  same  time  with  Volger 
and  Bischof.  According  to  Professor  Dana,  I  "  add  to  the  misrep- 
resentation by  means  of  the  strange  conclusion  that,  because  such 
writers  hold  that  crystals  may  undergo  certain  alterations  in  com- 
position, therefore  they  believe  that  rocks  of  the  same  constitution 
may  undergo  the  same  changes."  This  "  strange  conclusion "  I 
have  always  supposed  to  be  Professor  Dana's  own.  No  one  has  per- 
haps asserted  it  so  clearly  or  so  broadly  as  himself,  and  I  shall  there- 
fore quote  his  own  words  in  my  justification.  As  early  as  1845, 
in  an  article  entitled  Observations  on  Pseudomorphism  (Amer- 
ican Journal  of  Science  (1),  XLVIII.  92),  he  wrote  :  "  The  same 
process  which  has  altered  a  few  crystals  to  quartz  has  distributed 
silica  to  fossils  without  number,  scattered  through  rocks  of  all  ages. 
The  same  causes  that  have  originated  the  steatitic  scapolites  occa- 
sionally picked  out  of  the  rocks,  have  given  magnesia  to  whole 
rock-formations,  and  altered,  throughout,  their  physical  and  chemi- 
cal characters.  If  it  be  true  that  the  crystals  of  serpentine  are 
pseudomorphous  crystals,  altered  from  chrysolite,  it  is  also  true,  as 
Breithaupt  has  suggested,  that  the  beds  of  serpentine  containing 
them  are  likewise  altered,  though  often  covering  square  leagues  in 


320  ORIGIN   OF   CRYSTALLINE  ROCKS.  [XIII. 

extent,  and  common  in  most  primary  formations.  The  beds  of 
steatite,  the  still  more  extensive  talcose  formations,  contain  every- 
where evidence  of  the  same  agents."  Again,  in  1854,  in  his  Min- 
eralogy, 4th  edition  (page  226),  Professor  Dana,  after  a  complete 
list  of  pseudomorphs,  compiled  from  the  writers  of  the  school  in 
question,  says  :  "  These  examples  of  pseudomorphism  should  be 
understood  as  cases  not  simply  of  alteration  of  crystals,  but  in  many 
instances  of  changes  in  beds  of  rock.  Thus  all  serpentine,  whether 
in  mountain-masses  or  the  simple  crystal,  has  been  formed  through 
a  process  of  pseudomorphism,  or  in  more  general  language,  of  metamor- 
phism;  the  same  is  true  of  other  magnesian  rocks,  as  steatitic,  tal- 
cose, or  chloritic  slates.  Thus  the  subject  of  metamorphism,  as  it  bears 
on  all  crystalline  rocks,  and  of  pseudomorphism,  are  but  branches  of  one 
system  of  phenome?ia."  If  there  could  be  any  doubt  as  to  the  mean- 
ing of  the  words  which  I  have  italicized  in  quoting  them  from 
Professor  Dana,  it  is  removed  by  his  language  in  1858.  Then,  as 
now,  adversely  criticising  my  views  on  this  question,  he  refers  to 
the  statements  above  cited,  made  in  1845  and  1854,  as  expressions 
of  his  doctrine,  mentioning  especially  the  first  one,  in  which  he 
says,  "metamorphism  is  spoken  of  as  pseudomorphism  on  a  broad 
scale."  (American  Journal  of  Science  (2),  XXV.  445.)  I  confess 
that  I  do  not  understand  Professor  Dana,  when  in  his  last  criticism 
of  me,  fourteen  years  after  the  one  just  quoted,  he  reproaches  me 
with  having  charged  him  with  holding  the  doctrine  that  "  regional 
metaphorphism  is  pseudomorphism  on  a  grand  scale  "  ;  and  declares 
that  he  makes  no  such  remark,  neither  expresses  the  sentiment  in 
his  Mineralogy  of  1854. 

With  these  citations  before  us,  and  remembering  the  views  of 
Scheerer,  and  the  later  ones  of  Delesse,  together  with  the  language 
of  the  latter  in  his  essay  on  Pseudomorphs,  let  us  notice  the  words 
of  Naumann,  addressed  to  Delesse  in  1861,  in  allusion  to  the  essay 
in  question  :  "  Permit  me  to  express  to  you  my  satisfaction  for  the 
ideas  enunciated  in  your  memoir  on  Pseudomorphs,  —  ideas  which 
my  friend  Scheerer  will  doubtless  share  with  myself"  (idees  que  mon 
ami  M.  Scheerer  partagera  sans  doute  comme  moi-mem.e).  Then  fol- 
lows the  language  which  I  have  quoted  in  my  address,  in  which  he 
combats  the  error  of  those  who  hold  that  gneisses,  amphibolites, 
and  other  crystalline  rocks  are  "  the  results  of  metainorphic  epi- 
genesis,  and  not  original  rocks,"  and  adds,  "  It  is  precisely  because 
pseudomorphism  Juts  so  often  been  confounded  with  metamorphism  that 
this  error  has  found  acceptance."  (Bull.  Soc.  Geol.  de  France  (2), 


XIIL]  ORIGIN   OF  CRYSTALLINE  ROCKS.  321 

XVIII.  678.)  The  reader  must  now  judge  whose  opinions  it  is  that 
are  here  denounced  as  erroneous,  and  whether  Naumann  was  on 
the  side  of  Professor  Dana,  or,  with  Delesse,  on  the  side  of  Scheerer 
and  myself.  I  insist  the  more  strongly  on  this  matter,  because 
Professor  Dana  not  only  declares  that  Delesse  and  Naumann  have 
always  avowed  the  doctrines  of  the  transmutationist  school,  and  do 
not  in  any  way  whatever  countenance  my  views,  but  implies  that  I 
have  dealt  unfairly  with  these  authorities. 

Professor  Dana  says,  "  If  there  was  any  occasion  for  a  notice  of 
my  opinions,  a  critic  of  1871  should  have  referred  to  the  formal 
expression  of  them  in  my  Manual  of  Geology,  first  published  in 
1863.  The  reader  will  there  find  the  diagenesis  of  Giimbel,  which 
Mr.  Hunt  takes  occasion  to  commend,  ....  with  but  a  brief  allu- 
sion to  pseudomorphism."  The  doctrine  of  diagenesis,  it  is  hardly 
necessary  to  say,  I  have  never  attributed  to  Giimbel,  nor  does  he 
claim  it  It  is  the  old  doctrine  of  Hutton,  Playfair,  and  Boue,  is 
taught  by  Bischof  (Chemical  Geology,  III.  318,  325.  342),  and  per- 
vades my  papers  of  1859  and  1860,  already  referred  to.  But  while 
it  has  been  generally  admitted  that  what,  in  my  address,  I  have 
called  the  first  class  of  crystalline  rocks  (consisting  chiefly  of  quartz 
and  aluminous  silicates)  might  result  from  the  molecular  re- 
arrangement of  the  elements  of  clay  and  sand-rocks,  I  maintained 
in  those  papers  that  what  I  have  called  the  crystalline  rocks  of  the 
second  class  (in  which  protoxide-silicates  predominate)  have  been 
generated,  by  a  similar  process,  from  aqueous  deposits  of  chemically 
formed  silicates.  This  view,  advanced  by  me  in  1860,  having  been 
adopted  by  Delesse  and  by  Giimbel  to  explain  the  origin  of  the 
various  magnesian  silicated  rocks  hitherto  generally  regarded  as 
the  product  of  epigenesis,  the  latter  has  proposed  to  designate  the 
process  as  diagenesis  ;  a  term  which  I  adopt,  as  one  well  fitted  to 
denote  the  generation  of  all  kinds  of  crystalline  rocks  through  a 
molecular  rearrangement  of  sedimentary  deposits,  of  whatever 
origin.  Professor  Dana,  in  common  with  most  other  geologists, 
admits  in  his  Manual  of  Geology  the  old  conception  of  the  pro- 
duction by  diagenesis  from  mechanical  sediments  of  the  rocks  of  the 
first  class,  but  in  the  case  of  serpentine  and  steatite  declares  them 
to  have  been  formed  by  epigenic  pseudomorphism  or  chemical  alter- 
ation of  pyroxenic  and  other  crystalline  rocks  ;  the  origin  of  which 
is  by  him  left  entirely  unexplained.  It  is  true  that  his  allusions  to 
pseudomorphism  in  that  volume  are  confined  to  very  brief  notices 
on  pages  704  and  710  ;  a  fact  which  is  the  more  noticeable,  when  we 
14*  u 


322  ORIGIN   OF  CRYSTALLINE   ROCKS.  [XIII. 

recall  that  the  author  had  formerly  expressed  the  belief  "  that  pseu- 
domorphism will  soon  constitute  one  of  the  most  important  chap- 
ters in  geological  treatises."  (American  Journal  of  Science  (1), 
XL VIII.  66.)  That  Professor  Dana  has  receded  from  the  extreme 
views  on  this  subject  which  he  maintained  from  1845  to  1858,  and 
which  I  have  constantly  opposed,  seems  probable  ;  but  until  he 
formally  rejects  them,  the  student  of  geology  will  not  unnaturally 
suppose  that  he  still  gives  the  sanction  of  his  authority  to  the 
doctrine  which  he  so  long  taught  without  any  qualification,  but 
now  repudiates,  that  "  metamorphism  is  pseudomorphism  on  a  broad 
scale" 

[In  the  Neues  Jahrbuch  fur  Mineralogie  for  November,  1872 
(page  865),  appeared  a  note  from  the  venerable  Carl  Friedrich  Nau- 
niann  (who  has  since  died  at  an  advanced  age),  in  which  he  com- 
ments upon  my  interpretation  of  his  letter  to  Delesse.  He  begins 
by  saying  that  I  have,  in  my  address  in  1871,  cited  some  passages 
from  that  letter,  of  which  he  then  proceeds  to  repeat  the  substance, 
and  adds  :  "  Although  I  am  still  strongly  opposed  to  the  excesses 
of  the  metamorphic  doctrine,  I  cannot  explain  how  Professor  Sterry 
Hunt  can,  from  the  extracts  of  my  letter  to  Delesse,  conclude  that 
I  regard  those  cases  of  pseudomorphism  upon  which  the  theory  of 
metamorphism  is  grounded  as  in  great  part  only  examples  of  asso- 
ciation and  development,  and  also  as  a  result  of  a  simultaneous  and 
original  crystallization,  and  that  my  view  is  identical  with  his  own, 
which  he  first  put  forth  in  the  year  1853." 

Upon  this  I  have  to  remark  that,  instead  of  citing  in  my  address 
extracts  from  his  published  letter  to  Delesse,  I  gave  therein  a  trans- 
lation of  the  whole  letter,  with  the  exception  of  the  first  three  lines, 
which  are,  however,  given  above,  with  some  other  extracts,  in  my 
reply  to  Dana's  criticisms.  From  this  language  I  conclude  that 
Naumann  knew  my  address  only  through  these  misleading  criticisms 
and  my  reply  thereto.  In  the  next  place,  it  is  not  clear  what  were 
the  excesses  of  the  metamorphic  doctrine  which  he  still  condemned 
in  1872.  He,  as  we  have  shown  from  his  Lehrbuch  (ante,  page  294), 
regarded  gneisses  and  similar  rocks  as,  for  the  most  part,  in  some 
unexplained  way,  of  plutonic  origin,  though  he  admitted  their  pro- 
duction in  certain  cases  by  the  alteration  of  sediments,  agreeable  to 
the  Huttonian  view  of  diagenesis  ;  while  in  the  letter  above  men- 
tioned he  characterizes  as  erroneous  the  very  different  notion  that 
all  "  gneisses,  amphibolites,  etc.,"  are  "  the  results  of  metamorphic 
epigenesis."  From  his  language  in  1872,  however,  it  would  appear 


XIII.]  ORIGIN   OF   CRYSTALLINE   ROCKS.  323 

that,  in  his  opinion,  such  rocks,  once  formed,  may  become  the  sub- 
jects of  epigenic  pseudomorphism,  and  be  metamorphosed,  as  sup- 
posed by  Bischof,  Dana,  and  others,  into  serpentines,  steatites,  etc. 
In  this  case  his  implied  sympathy,  in  1861,  with  the  teachings  of 
Seheerer,  who,  in  denying  the  epigenic  origin  of  the  serpentine  asso- 
ciated with  chrysolite  and  many  similar  cases,  had  struck  a  blow,  in 
the  language  of  Naumann,  at  "  those  cases  of  pseudomorphism  upon 
which  the  theory  of  metamorphism  is  grounded  "  ;  and  finally,  his 
congratulations  to  Delesse  (who  had  j  ust  declared  that  often  "  the  so- 
called  metamorphism  finds  its  natural  explanation  in  envelopment," 
and  asserted  the  view  of  Seheerer  and  myself  that  much  of  what 
has  been  regarded  as  pseudomorphism  has  no  other  basis  than  the 
observed  associations  of  mineral  species)  could,  in  my  opinion,  ad- 
mit of  no  other  interpretation  than  the  one  which  I  in  1871  gave 
to  it.  There  is  a  confusion,  not  to  say  a  contradiction,  in  these 
expressed  views  of  the  venerable  teacher,  which  it  is  not  easy  to 
explain. 

Nothing  has  been  further  from  my  intention  than  to  misrepresent 
the  views  either  of  Naumann  or  of  Dana  ;  and  my  error,  if  I  have 
fallen  into  one,  arises  from  the  difficulty  of  knowing  their  real 
opinions  upon  the  matters  in  discussion.  Let  Professor  Dana  de- 
fine, as  clearly  as  I  have  clone,  his  present  views  as  to  the  origin  of 
magnesian  rocks,  both  those  made  up  of  chrysolite  and  pyroxenic 
minerals,  and  those  composed  of  serpentine,  steatite  and  chlorite, 
which  he  has  supposed  to  come  from  an  epigenesis  of  the  former  ; 
let  him  tell  us  whether  he  holds  the  doctrine  of  pseudomorphic 
metamorphism  which  he  taught  in  1845,  1854  and  1858,  and 
which,  as  I  have  shown,  was  held  by  Delesse  as  late  as  1857,  or  that 
doctrine  so  long  maintained  by  me,  which  the  latter  adopted  in 
1861.  Such  a  definition  would  be  eminently  satisfactory  to  those 
who  look  to  him  as  a  teacher  in  science,  and  would  prevent  any 
further  misconception  or  unintentional  misrepresentation  of  his 
views.] 

Professor  Dana,  having  clearly  defined  the  proposition  that  the 
chemical  alterations  which  are  recognized  in  individual  crystals  are 
to  be  conceived  as  extending  to  rock-masses,  and  having,  more- 
over, asserted  that  the  principle  of  the  identity  of  metamorphism 
and  pseudomorphism  "  bears  on  all  crystalline  rocks,"  is  logically 
committed  to  all  the  deductions  as  to  the  changes  of  rocks  which 
the  transmutationist  school  has  drawn  from  the  supposed  alteration 
of  minerals.  By  reference  to  the  table  of  pseudomorphs  in  the 


324  ORIGIN   OF   CRYSTALLINE  ROCKS.  [XIII. 

fourth  edition  of  Dana's  Mineralogy,  it  will  be  seen  that  each  one 
of  the  metamorphoses  of  rocks  mentioned  in  the  above  extract  from 
my  address  is  based  upon  an  asserted  epigenic  change  or  conversion 
of  the  constituent  species.  I  shall,  however,  show,  in  addition,  that 
in  each  case  the  application  of  the  principle  to  rock- masses  has  been 
recognized  by  one  or  more  of  the  authorities  already  named,  and 
that  the  so-called  caricature  has  been  drawn  by  their  own  hands. 
It  would  be  easy,  did  space  permit,  to  extend  greatly  this  list  of 
supposed  transmutations.  The  various  associations  of  rocks  and 
minerals  in  nature,  when  interpreted  according  to  the  canons  of  this 
school,  seem,  in  fact,  as  remarked  by  Professor  Warrington  Smyth, 
in  his  address  already  quoted,  "  to  offer  a  premium  to  the  ingenious 
for  inventing  an  almost  infinite  series  of  possible  combinations  and 
permutations."  Before  proceeding  further  it  is  to  be  noted  that  no 
distinction  can,  in  many  cases,  be  established  between  the  results 
of  alteration  (or  partial  replacement)  and  substitution  (or  complete 
replacement)  ;  since  successive  alterations  may  give  the  same  pro- 
duct as  direct  substitution.  Thus,  for  example,  quartz  might  be 
directly  replaced  by  calcite,  or  else  first  altered  to  a  silicate  of  lime, 
which,  in  its  turn,  might  be  changed  to  carbonate.  The  alteration 
of  quartz  to  a  silicate  of  magnesia,  and  that  of  both  pyroxene  and 
pectolite  to  calcite,  is  maintained  by  the  writers  of  the  present 
school. 

Metamorphosis  of  granite  or  gneiss  to  limestone  :  —  Calcite,  we  are 
told,  is  pseudomorphous  of  quartz,  of  feldspar,  of  pyroxene,  and  of 
garnet,  besides  other  species ;  it  moreover  replaces  both  orthoclase 
and  albite  "by  some  process  of  solution  and  substitution."  (Dana's 
Mineralogy,  5th  edition,  361.)  Since  quartz,  orthoclase,  and  albite 
can  be  replaced  by  calcite,  the  transmutation  of  granite  or  gneiss 
into  limestone  presents  no  difficulty.  [In  the  opinion  of  Messrs. 
King  and  Rowney,  the  crystalline  limestones  of  Tyree  in  the 
Hebrides,  those  of  Aker  in  Sweden,  and  similar  limestones  in  the 
Laurentian  of  North  America,  were  at  one  time  beds  of  gneiss, 
diorite,  and  other  silicated  rocks,  which  have  been  changed  by  an 
epigenic  process.  (Annals  and  Magazine  of  Natural  History  for 
1874,  Vol.  XIII.  page  390.)  Volger  has  also  asserted  a  similar 
origin  for  certain  gneissoid  limestones.] 

Metamorphosis  of  limestone  to  dolomite  :  —  This  change  is  main- 
tained by  Von  Buch,  Haidinger,  and  many  others.  I  am  blamed  for 
mentioning  in  connection  with  this  school  the  name  of  Haidinger, 
who,  Professor  Dana  says,  "  never  wrote  upon  the  subject  of  the 


XIII.]  ORIGIN  OF   CRYSTALLINE   ROCKS.  325 

alteration  of  rocks."  It  will,  however,  be  noticed,  that  his  name 
has  been  quoted  by  Delesse  with  those  of  Bischofj  Blum,  and  oth- 
ers as  a  disciple  of  this  school,  and  it  has  never  before  been  ques- 
tioned that  Haidinger  was  the  first,  if  not  to  suggest,  to  clearly  set 
forth,  the  theory  of  the  supposed  conversion  of  limestone  into 
dolomite  by  the  action  of  magnesian  solutions,  aided  by  heat  and 
pressure,  —  a  theory  which  I  have  elsewhere  refuted.  (Bischof, 
Chern.  Geol.,  III.  155,  158  ;  Zirkel,  Petrographie,  I.  246  ;  Liebig 
and  Kopp,  Jahresbericht,  1847-48,  1289  ;  and  American  Journal 
of  Science  (2),  XXVIII.  376). 

Metamorphosis  of  dolomite  to  serpentine  :  —  This  change  is  main- 
tained by  G.  Rose  (Bischof,  Chem.  GeoL,  IL  423),  and  by  Dana 
(American  Journal  of  Science  (3),  III.  89). 

Metamorphosis  of  granite,  granulite,  and  eclogite  directly  into  ser- 
pentine, chlorite,  and  talc  :  —  These  transmutations  are  maintained 
by  Miiller,  and  adopted  by  Bischof.  (Chem.  Geol.,  II.  424,  434.) 

Metamorphosis  of  limestone  to  granite  or  gneiss  :  —  This  is  taught 
by  Blum  and  Volger.  (Chem.  GeoL,  II.  186  ;  III.  431.) 

Having  thus  given  the  authorities  for  the  examples  cited  in  my 
address,  I  may  notice  some  further  illustrations  of  the  doctrine 
from  the  pages  of  Bischof  s  work  already  quoted.  Metamorphosis 
of  diorite,  hornblende-rock,  and  labradorite  to  serpentine  ;  G.  Rose, 
Breithaupt,  Von  Rath  (II.  417,  418) :  diorite  and  hornblende-slate 
to  talc-slate  and  chlorite-slate ;  G.  Rose  (III.  312)  :  mica-slate  to 
talc-slate  and  steatite,  and  mica  to  serpentine,  steatite,  and  talc  ; 
Blum,  C.  Gmelin  (II.  405,  468)  :  quartz-rock  to  steatite  ;  Blum  (II. 
468). 

[That  the  extravagant  views  of  the  transnmtationists,  as  set  forth 
in  the  preceding  pages,  though  now  denied  by  Professor  Dana,  are 
still  maintained  by  others,  is  well  shown  by  two  recent  publica- 
tions. In  one  of  these,  just  referred  to,  Messrs.  King  and  Rowney 
h  ive  gone  even  further  than  their  predecessors.  Not  content  with 
teaching  the  conversion  of  feldspar,  quartz,  hornblende,  pyroxene, 
and  chondrodite  into  calcite,  they  imagine  that  serpentine,  which, 
according  to  Dana  and  others,  results  in  all  cases  from  the  alteration 
of  silicated  or  carbonated  species,  may  itself  become  the  subject  of 
epigenic  change,  and  be  converted  into  calcite.  The  ophicalce 
rocks,  which  are  mixtures  of  serpentine  and  carbonate  of  lime, 
have,  according  to  King  and  Rowney,  been  formed  in  this  manner 
from  serpentine  ;  and  they  further  imagine  this  process  to  have  been 
so  guided  as  to  leave  the  unchanged  portions  of  the  serpentine  with 


326  GEOGNOSY  OF  THE  APPALACHIANS.  [XIII. 

the  forms  of  a  foraminiferal  organism,  the  Eozoon  Canadense  of 
Dawson.  This  singular  supplement  to  the  hypothesis  of  epigenic 
change  recalls  the  notion  of  the  older  naturalists,  who,  rather  than 
admit  the  organic  origin  of  shells  found  in  the  rocks,  imagined 
them  to  have  been  generated  by  a  plastic  force.  It  is  evident  that 
it  makes  little  difference  what  mineral  species  is  taken  as  a  starting- 
point  for  these  transformations,  and  Dr.  Genth  has  assumed  corun- 
dum. In  a  recent  paper  (Proceedings  of  the  American  Philosophi- 
cal Society,  September  19,  1873)  he  has  discussed  various  facts 
observed  in  the  association  and  envelopment  of  the  minerals  associ- 
ated with  it,  and  concludes  that  there  have  been  formed  from  corun- 
dum, by  epigenesis,  spinel,  tourmaline,  nbrolite,  cyanite,  paragonite, 
damourite  and  other  micas,  chlorite,  and  probably  various  feld- 
spars. According  to  him,  great  beds  of  micaceous  and  chloritic 
schists  have  resulted  from  the  transformation  of  corundum,  and 
even  the  beds  of  bauxite,  a  mixture  of  hydrous  aluminic  and  ferric 
oxides,  allied  to  limonite,  which  abounds  in  certain  tertiary  depos- 
its, were  once  corundum  or  emery,  from  which  this  amorphous 
hydrate  is  supposed  to  have  been  derived  by  a  retrograde  metamor- 
phosis ;  a  striking  example  of  the  strange  conclusions  to  which  this 
doctrine  of  epigenic  pseudomorphism  may  lead.  The  corundum- 
bearing  vein-stones  present  close  resemblance  in  the  grouping  and 
association  of  minerals  to  the  granitic  and  calcareous  vein-stones 
described  in  Essay  XI.  of  the  present  volume.  See,  further,  the 
author's  criticisms  on  this  subject,  Proceedings  Boston  Society  of 
Natural  History,  March  4,  1874.] 

Coming  now  to  his  criticism  of  the  first  part  of  my  address,  with 
regard  to  New  England  rocks,  Professor  Dana  asserts  that  "  there 
are  gneisses,  mica-schists,  and  chloritic  and  talcoid  schists  in  the 
Taconic  series."  I  have,  however,  shown  in  my  address  that  Em- 
mons,  the  author  of  the  Taconic  system,  expressly  excluded  there- 
from the  crystalline  rocks,  which  he  included  in  an  older  primary 
system  ;  excepting,  however,  certain  micaceous  and  talcose  beds, 
which  he  declared  to  be  recomposed  rocks,  made  up  from  the  ruins 
of  the  primary  schists,  and  distinguished  from  these  by  the  absence 
of  the  characteristic  crystalline  minerals  which  belong  to  the  Green 
Mountain  primary  schists. 

Again,  Professor  Dana  states  that  I  make  the  crystalline  schists 
of  the  White  Mountains  a  newer  series  than  the  Green  Mountain 
rocks.  Such  a  view  of  their  geognostical  relations  has  been  main- 
tained for  the  last  generation  by  the  Messrs.  Rogers,  Logan,  and 


XIIL]  GEOGNOSY  OF  THE  APPALACHIANS.  327 

many  others,  all  of  whom  assigned  the  crystalline  schists  of  the 
White  Mountains  to  a  higher  geological  horizon  than  those  of 
the  Green  Mountains.  In  support  of  this  view  of  their  relative 
antiquity,  I  have,  however,  brought  together  observations  from 
South  Carolina,  Pennsylvania,  Michigan,  Ontario,  and  Maine,  all  of 
which  point  to  the  same  conclusion  ;  and  I  might  now  add  similar 
evidence  from  New  Brunswick  and  from  Nova  Scotia.  My  "  chrono- 
logical arrangement "  of  New  England  crystalline  rocks,  as  it  is 
called  by  Professor  Dana,  so  far  as  it  is  my  own,  is  limited  to  my 
affirmation  that  they  are  all  of  pre-Cambrian  age  ;  in  proof  of 
which  it  need  only  be  mentioned  that  the  crystalline  schists  of  both 
the  types  in  question  are,  in  southern  New  Brunswick,  directly 
overlaid  by  uncrystalline  shales,  sandstones  and  conglomerates, 
made  up  in  part  of  the  ruins  of  these,  and  holding  a  Cambrian 
(Menevian)  fauna. 

As  regards  the  mica-schists  with  staurolite,  cyanite,  andalusite, 
and  garnet,  I  have  in  my  address  pointed  out  the  fact  that  they 
appear  to  belong  to  a  great  series  of  rocks,  very  constant  in  charac- 
ter, which  have  a  continuous  outcrop  from  the  Hudson  River  to 
the  St  John,  a  distance  of  five  hundred  miles,  and  in  the  latter 
region  are  clearly  pre-Cambrian.  I  have,  moreover,  brought  to- 
gether the  evidence  of  observers  in  other  parts  of  North  America, 
in  Great  Britain,  in  continental  Europe,  and  in  Australia,  showing 
that  similar  crystalline  schists,  holding  these  same  minerals,  always 
occupy,  in  these  regions,  a  similar  geological  horizon.  Professor 
Dana  hereupon  inquires  whether  any  one  has  yet  proved  that  these 
mineral  characters  are  restricted  to  rocks  of  a  certain  geological 
period.  I  answer,  that  in  opposition  to  these  facts,  it  has  not  yet 
been  proved  that  they  belong  to  any  later  geological  period  than 
the  one  already  indicated  ;  and  that  it  is  only  by  bringing  together 
observations,  as  I  have  done,  that  we  can  ever  hope  to  determine 
the  geological  value  of  these  mineral  fossils.  In  no  other  way  did 
William  Smith  prove,  in  Great  Britain,  the  value  of  organic  fossils, 
and  thus  lay  the  foundations  of  paleontological  geology. 


XIV. 


THE  GEOLOGY  OF  THE  ALPS. 

This  review  appeared  in  the  American  Journal  of  Science  for  January,  1872,  and 
serves  to  throw  much  light  upon  many  important  and  still  debated  points  of  geology. 
I  have  added  as  an  appendix  to  the  present  reprint  the  recent  conclusions  of  Favre, 
and  the  statements  of  Fillet,  which  serve  to  confirm  certain  positions  assumed  in  the 
review,  and  elsewhere  in  this  volume.* 

SINCE  the  days  of  De  Saussure,  the  Alps  have  been  the  ob- 
ject of  constant  study.  No  other  portion  of  Europe  offers  so 
many  problems  of  interest  to  the  geologist  and  the  physical 
geographer  as  this  great  mountain-chain,  whether  we  consider 
its  lakes,  glaciers,  and  moraines,  its  curiously  disturbed  and 
inverted  fossiliferous  strata,  which  seem,  at  first  sight,  arranged 
for  the  confusion  alike  of  paleontologists  and  stratigraphists,  or 
the  crystalline  rocks  which  form  its  highest  summits.  To  give 
a  list  of  the  various  investigators  who  have  contributed  their 
share  to  the  elucidation  of  this  region  would,  of  itself,  be  no 
slight  task,  and  would  besides  be  foreign  to  our  present  pur- 
pose ;  which  is  to  call  attention  to  the  learned  work  of  Pro- 
fessor Alphonse  Favre  of  Geneva,  in  which  he  has  given  us  the 
results  of  more  than  twenty-five  years  of  labor  in  the  study  of 
Alpine  geology,  chiefly  in  Savoy  and  the  adjacent  parts  of 
Piedmont  and  Switzerland,  embracing  Mont  Blanc  and  its 
vicinity.  It  is  now  twelve  years  since  the  present  writer  had 
occasion  to  review,  in  the  American  Journal  of  Science  ((2), 
XXIX.  118),  some  points  in  Alpine  geology  raised  by  our 
author  in  his  memoir  "  Sur  les  terrains  liassique  et  keuperien  de 

*  Recherches  Geologiques  dans  les  parties  de  la  Savoie,  du  Piemont,  et  de 
la  Suisse  voisines  du  Mont  Blanc,  avec  un  Atlas  de  32  planches,  par  Alphonse 
Favre,  Professeur  de  Geologic  a  1' Academic  de  Geneve.  3  Vols.  8vo.  Paris. 
1867. 


XIV.]  THE   GEOLOGY  OF  THE  ALPS.  329 

la  Savoie,"  published  in  1859.  Since  that  time  the  views  then 
maintained  hy  Favre  have,  in  spite  of  much  opposition,  gained 
ground,  and  are  set  forth  at  length  in  the  present  work,  sup- 
ported by  an  amount  of  evidence  which  seems  convincing. 
We  shall  endeavor  from  its  pages  to  present  a  condensed  sum- 
mary of  our  present  knowledge  of  the  structure  of  Mont 
Blanc  and  the  adjacent  regions. 

The  crystalline  rocks  of  the  Alps,  as  first  shown  by  Studer, 
do  not  form  a  continuous  chain,  but  appear  as  distinct  masses, 
separated  from  each  other  by  uncrystalline  sedimentary  de- 
posits, generally  fossiliferous.  According  to  Desor,  there  are 
between  Xice  and  the  plains  of  Hungary  not  less  than  thirty- 
four  such  areas,  standing  up  like  islands  from  out  of  the  sedi- 
mentary rocks,  and  presenting  for  the  most  part  a  fan-like 
structure  (en  eventail).  Of  these  masses  of  crystalline  rock, 
Mont  Blanc  is  the  most  remarkable,  and  is  described  by  Elie 
de  Beaumont  as  "  rising  through  a  solution  of  continuity  in  the 
secondary  strata,  which  may  be  compared  to  a  great  button- 
hole." The  length  of  this  area  of  crystalline  rock,  measured 
from  the  Col  du  Bonhomme  on  the  southwest  to  Saxon  in  the 
Yalais  on  the  northeast,  is  fifty-nine  kilometres,  while  its 
breadth,  from  Chamonix  on  the  northwest  to  Entreves  near 
Courmayeur  on  the  southeast,  is  fourteen  kilometres.  The 
length  of  the  central  mass  of  protogine  is,  however,  only 
twenty-seven  kilometres.  Of  the  numerous  peaks  in  this 
area  the  highest  attains  an  elevation  of  4,810  metres  above  the 
level  of  the  sea,  being  3,760  metres  above  the  valley  of 
Chamonix,  and  3,520  metres  above  the  valley  of  Entreves. 
This  great  mass  is  described  by  Favre  as  supported  at  the 
four  corners  by  as  many  buttresses  rising  from  the  surrounding 
valleys,  and  known  as  the  Cols  de  Balme,  de  Voza,  de  la 
Seigne,  and  de  Ferret.  The  distance  between  the  two  valleys 
just  named  is  only  13,500  metres,  and  the  boldness  with 
which  the  mountain  rises  from  them  is  strikingly  apparent  if 
we  take  the  Col  de  1'Aiguille  du  Midi  and  the  Col  du  Geant, 
which  are  about  3,460  metres  above  the  sea,  and  distant  from 
each  other  5,000  metres,  giving  a  slope  of  about  30°.  A  still 


330  THE   GEOLOGY  OF  THE  ALPS.  [XIV. 

greater  inclination  is  obtained  if  we  choose,  instead  of  these, 
the  summits  of  the  Aiguilles  which  bear  the  same  names,  and, 
although  now  isolated,  represent  portions  of  the  former  mass 
of  Mont  Blanc. 

The  crystalline  rocks  of  this  region  present  two  types  :  first, 
the  protogines  which  form  the  centre ;  and,  second,  the  crys- 
talline schists  which  occupy  the  flanks  and  form  the  Aiguilles 
Eouges.  These  schists  are  also  found  at  a  great  elevation  on 
the  mountain;  at  the  Grands  Mulcts  (4,666  metres)  the  rocks 
are  talcose  and  quartzose  schists  with  graphite,  hornblende, 
epidote,  talc,  and  asbestus,  and  similar  rocks  and  minerals  are 
found  from  thence  to  the  summit.  The  protogines  themselves, 
according  to  the  evidence  of  nearly  all  who  have  studied  them, 
are  stratified  rocks,  gneissic  in  structure,  and  pass  in  places 
into  more  schistose  varieties,  though  Favre  regards  the  distinc- 
tion between  these  and  the  crystalline  schists  proper  as  one 
clearly  marked.  The  outlines  presented  by  the  weathering  of 
the  protogine  are  very  unlike  the  rounded  forms  assumed  by 
true  granite  rocks.  According  to  Delesse,  the  rock  to  which 
Jurine  gave  the  name  of  protogine  is  a  talco-micaceous  granite 
or  gneiss,  made  up  of  quartz,'  generally  more  or  less  grayish  or 
smoky  in  tint,  with  orthoclass,  grayish  or  reddish  in  color,  and 
a  white  or  greenish  oligoclase  with  characteristic  striae,  often 
penetrated  with  greenish  talc.  The  mica  (biotite),  which  some 
previous  observers  had  mistaken  for  chlorite,  is  dark  green  in 
color,  becoming  of  a  reddish  bronze  by  exposure.  It  is  binaxial, 
nearly  anhydrous,  and  contains  a  large  portion  of  ferric  oxide. 
The  composition  of  the  protogine  rock,  as  a  whole,  differs  from 
that  of  ordinary  granite,  according  to  Delesse,  only  in  the 
presence  of  one  or  two  hundredths  of  iron-oxide  and  magnesia. 
The  name  of  arkesine  was  given  by  Jurine  to  a  variety  of 
protogine  containing  chlorite  with  hornblende,  and  sometimes 
sphene.  Among  the  other  crystalline  rocks  of  the  Alps  are 
various  talcose  and  chloritic  schists,  with  steatites,  chromifer- 
ous  serpentines,  diallage  rocks,  diorites,  and  euphotides,  asso- 
ciated with  beds  of  petrosilex  or  eurite,  frequently  porphyritic. 
Highly  micaceous  schists,  often  quartzose,  and  holding  .garnet, 


XIV.]  THE  GEOLOGY   OF  THE  ALPS.  331 

staurolite,  and  cyanite,  are  also  met  with  among  the  crystalline 
rocks  of  the  Alps.  A  great  belt  of  serpentine  and  chloritic 
schists,  traced  for  a  long  distance,  may  be  seen  at  the  base 
of  the  Montanvert  overlaid  by  the  euritic  porphyries,  into 
which  they  appear  to  graduate;  the  whole  series,  here  sup- 
posed to  be  inverted,  dipping  at  about  60°  from  the  valley  of 
Chamonix  toward  Mont  Blanc,  and  overlaid  by  the  more 
massive  gneiss  or  protogine.  The  chloritic  and  talcose  schists 
of  the  Alps  have  close  resemblances  with  those  of  the  Urals, 
and,  as  Damour  has  shown,  contain  a  great  many  mineral  spe- 
cies in  common  with  them.  Favre  has,  moreover,  remarked 
the  strong  likeness  between  the  chloritic  and  talcose  schists 
and  the  mica-scliists  with  staurolite  of  the  western  Alps  and 
those  found  in  Great  Britain. 

Granite,  though  not  abundant  in'  the  vicinity  of  Mont  Blanc, 
occurs  in  several  localities,  the  best  known  of  which  is  Valor- 
sine,  where  a  porphyroid  granite  with  black  mica  forms  con- 
siderable masses,  and  sends  large  veins  into  the  adjacent  gneiss. 
These,  with  others  found  at  the  Col  de  Balnie  and  in  the 
Aiguilles  Rouges,  appear  to  be  true  eruptive  granites.  Numer- 
ous small  veins  met  with  among  the  crystalline  schists  in  the 
gorge  of  Trient  appear,  however,  to  belong  to  what  I  have 
described  as  endogenous  granites.  (Ante,  page  193.)  Favre 
has  himself  maintained  that  they  are  the  results  of  aqueous 
infiltration,  and  has  noticed  the  fact  of  a  joint  running  longi- 
tudinally through  the  middle  of  many  of  them  as  an  evidence 
of  this  mode  of  formation. 

The  uncrystalline  strata  in  the  region  around  Mont  Blanc 
include  representatives  of  the  carboniferous,  triassic,  Jurassic, 
neocomian,  cretaceous,  and  tertiary.  The  existence  of  an  ap- 
parently carboniferous  flora,  and  its  intimate  association  with  a 
liassic  fauna,  has  long  been  a  well-known  fact  in  Alpine  geology. 
In  1859,  Favre  pointed  out  the  existence  of  a  zone  of  triassic 
rocks  in  this  region  represented  by  red  and  green  shales,  with 
sandstones,  gypsum,  and  a  cavernous  magnesian  limestone 
(cargneule).  These  rocks  had  long  before  been  referred  to  this 
period  by  Bueklaiid  and  Bakewell,  but  their  horizon  was  estab- 


332  THE   GEOLOGY   OF   THE  ALPS.  [XIV. 

lished  by  the  discovery  of  Favre  that  their  position  is  inter- 
mediate between  the  carboniferous  and  the  strata  containing 
Avicula  contorta  (the  Kossen  beds,  or  the  Rhaetic  beds  of 
Giimbel),  which  are  recognized  as  forming  a  passage  between 
the  trias  and  the  lias,  at  the  base  of  the  Jurassic  system.  To 
these,  to  the  northwest  of  Mont  Blanc,  succeed  the  higher 
members  of  the  system,  followed  by  the  neocomian,  the  creta- 
ceous, and  the  nummulitic  strata  of  the  eocene,  with  overlying 
sandstones  and  shales,  the  flysch  of  some  Alpine  geologists. 

Few  questions  in  geology  have  been  more  keenly  debated,  or 
given  rise  to  more  often-repeated  examinations,  than  the  asso- 
ciation of  a  carboniferous  flora  with  liassic  belemnites  in  the 
districts  of  Maurienne  and  Tarentaise,  to  the  southwest  of 
Mont  Blanc.  As  seen  at  Petit-Cceur,  the  schists,  with  impres- 
sions of  ferns  and  beds  of  anthracite,  were  so  long  ago  as  1828 
described  by  Elie  de  Beaumont  as  apparently  intercalated  in 
the  Jurassic  system.  Scipion  Gras,  and  Sismonda  after  him, 
have  agreed  in  regarding  the  rocks  as  constituting  one  great 
system,  which  according  to  Gras  is  of  carboniferous  age,  but 
with  a  Jurassic  fauna ;  while  De  Beaumont  and  Sismonda,  on 
the  contrary,  regarded  it  as  of  Jurassic  age,  but  with  a  carbon- 
iferous flora,  and  imagined  that  by  some  means  there  had  been 
in  this  region  a  local  survival  of  the  vegetation  of  the  palaeo- 
zoic period.  These  conclusions  were  accepted  by  many  geolo- 
gists, though  rejected  by  not  a  few.  A  brief  account  of  the 
controversy  up  to  that  date  will  be  found  in  the  American 
Journal  of  Science  for  January,  1860,  page  120;  and  in  the 
work  of  Favre  now  before  us  the  whole  matter  is  discussed  at 
great  length  in  Chapter  XXX.  The  anthracitic  system  of  the 
Alps,  as  recognized  by  Gras,  was  by  him  estimated  to  have  a 
thickness  of  from  25,000  to  30,000  feet,  and  included,  besides 
the  dolomites  and  gypsums  now  referred  by  Favre  to  the  trias, 
coal-plants  and  layers  of  anthracite,  together  with  limestones 
holding  belemnites  of  Jurassic  age.  Included  in  this  great 
system  were,  moreover,  gneissic,  micaceous,  and  talcose  rocks, 
with  graphite,  serpentine,  euphotide,  etc.,  all  of  which  were 
regarded  by  Gras  as  formed  by  the  local  alteration  of  portions 


XIV.]          THE  GEOLOGY  OF  THE  ALPS.          333 

of  the  anthracitic  system.  To  this  was  added  in  1860  the 
discovery  by  Fillet  of  nummulitic  beds  intercalated  in  the  same 
series  near  St.  Julien  in  Maurienne.  This  fact  was,  however,  in 
accordance  with  the  conclusion  previously  reached  by  Sismonda 
from  an  examination  of  Taninge,  that  "  the  plants  of  the  car- 
boniferous period  were  still  nourishing  while  the  seas  were 
depositing  the  rocks  of  the  nummulitic  period." 

The  question  involved  in  this  controversy  had  more  than  a 
local  interest,  since  it  touched  the  very  bases  of  paleontology, 
by  pretending  that  in  the  Alps  the  laws  of  succession  which 
elsewhere  prevail  were  suspended,  and  that  the  same  types  of 
vegetation  had  continued  unchanged  from  the  palaeozoic  to  the 
tertiary  period.  Already,  in  1841,  Favre  had  brought  forward 
the  suggestion  of  Voltz,  that  these  apparent  anomalies  might 
be  explained  by  inversions  of  the  strata ;  but  this  notion  was 
rejected  by  De  Mortillet  and  Murchison,  as  inadmissible  for  the 
section  at  Fetit-Cceur.  The  recognition  by  Favre,  in  1861,  of 
the  true  age  and  position  of  the  cargneules  and  their  associated 
rocks,  however,  threw  a  new  light  on  the  question,  for  it  was 
shown  that  these  triassic  rocks  were  interposed  at  Petit-Cceur 
between  the  limestones  holding  belemnites  and  the  schists  with 
coal-plants.  In  1861,  the  Geological  Society  of  France  held  its 
extraordinary  session  at  St.  Jean  in  Maurienne,  and  there  also 
the  succession  was  made  clearly  evident,  as  follows  :  nummu- 
litic, liassic,  infra-liassic,  triassic,  and  carboniferous;  the  last 
resting  on  crystalline  schists. 

Attempts  had  been  made  to  sustain  the  supposed  Jurassic  age 
of  the  so-called  anthracitic  formation,  by  maintaining  that  some 
at  least  of  the  coal-plants  were  Jurassic  forms ;  but  Heer,  who 
had  long  maintained  the  contrary,  published  in  1863  a  further 
study  of  the  fossil  flora  of  Switzerland  and  Savoy,  in  which 
he  showed  that  of  sixty  species  fourteen  are  peculiar  to  these 
regions,  while  forty-six  belong  to  the  carboniferous  flora  of 
Europe,  and  twenty-seven  are  common  with  that  of  North 
America.  One  species  only  has  been  identified  as  of  liassic  age, 
namely,  Odontopteris  cycadea  Brongn.,  and  is  found  in  a  locality 
near  Jurassic  belemnites,  but  associated  with  no  other  plant. 


334  THE   GEOLOGY   OF   THE  ALPS.  [XIV. 

Both  Lory  and  Fillet  now  admit  with  Favre  that  the  sup- 
posed paleontological  anomalies  of  this  region  have  no  exist- 
ence, and  that  this  anthracitic  system  includes  carboniferous, 
Jurassic,  and  nummulitic  strata  inverted  and  folded  upon  them- 
selves ;  nor  is  it  without  reason  that  Lory  in  this  connection 
remarks  upon  "  the  illusions  without  number  to  which  a  purely 
stratigraphical  study  of  the  Alps  may  give  rise."  To  this  we 
may  add  the  judgment  of  Dumont,  in  discussing  the  disturbed 
and  inverted  anthracite  system  of  the  Ardennes,  that  for  regions 
thus  affected  "  we  cannot  establish  the  relative  age  of  the  rocks 
from  their  inclination  or  their  superposition." 

These  conclusions  were  not,  however,  admitted  by  Sismonda, 
who,  in  1866,  presented  to  the  Eoyal  Academy  of  Sciences  of 
Turin  an  elaborate  memoir  on  the  anthracite  system  of  the 
Alps.*  In  this,  while  admitting  at  Petit-Coeur  the  existence 
of  evidence  of  more  or  less  contortion,  rupture,  and  overriding 
(emhevauchemeni)  of  the  strata,  he  still  maintains  that  the  an- 
thracitic system  of  Maurienne  and  Tarentaise  is  one  great  con- 
tinuous series  of  Jurassic  age,  from  the  fundamental  gneiss  and 
protogine,  upon  which  it  immediately  rests,  to  the  upper  mem- 
ber in  which  occur  thick  beds  of  anthracite,  with  an  abundant 
carboniferous  flora,  which  he  assigns,  however,  to  the  middle 
oolite  (Oxfordian) ;  the  great  mass  of  strata  below  being  re- 
ferred to  the  lias.  He  then  particularly  indicated  the  line  of 
the  great  Mont  Cenis  tunnel,  which,  commencing  in  the  upper 
anthracitic  member,  should  pass  downward  through  the  quartz- 
ites  and  gypsums,  thence  through  talcose  schists  and  limestones, 
as  far  as  Bardonecchia.  These  schists  and  limestones,  accord- 
ing to  him,  are  in  "  a  very  advanced  stage  of  metamorphism," 
and  include  eruptive  serpentines,  with  euphotide,  steatite,  and 
other  magnesian  rocks. 

Since  the  completion  of  the  tunnel,  Messrs.  Sismonda  and 
Elie  de  Beaumont  have  presented  to  the  Academy  of  Sciences 
of  Paris  an  extended  report  on  the  geological  results  obtained 
in  this  great  work.  It  is  accompanied  by  a  description  of  134 
specimens  of  the  rocks  collected  at  intervals  throughout  the  en- 
*  Memoirs  of  the  Acad.,  Second  Series,  XXIV  333. 


XIV.]  THE   GEOLOGY   OF   THE   ALPS.  335 

tire  distance  of  the  tunnel,  which,  it  will  be  remembered,  passes 
from  near  Modane  in  Savoy  to  Bardonecchia  in  Piedmont 
(about  fifteen  miles  to  the  southwest  of  Mont  Cenis),  a  distance 
of  12,220  metres.  The  direction  of  the  tunnel  is  N.  14°  W., 
and  the  dip  of  the  strata  throughout  nearly  uniform,  N.  55°  "W., 
at  an  angle  of  about  50°.  From  this  we  deduce  by  calculation 
that  the  vertical  thickness  of  the  strata  is  equal  to  nearly  60 
per  cent  of  the  distance  traversed,  or  in  round  numbers  about 
7,000  metres.  Of  this  not  less  than  5,831  metres,  beginning  at 
the  southern  extremity,  are  occupied  by  lustrous  and  more  or 
less  talcose  schists  with  crystalline  micaceous  limestones,  often 
cut  by  veins  of  quartz  with  chlorite  and  calcite.  Above  there 
are  515  metres  in  thickness  of  alternations  of  anhydrous  sul- 
phate of  lime  (karstenite)  with  talcose  schist  and  crystalline 
limestone.  The  anhydrite  enclosed  lamellar  talc  in  irregular 
nodules,  with  dolomite,  crystallized  quartz,  sulphur,  and  masses 
of  rock-salt.  This  was  overlaid  by  220  metres  of  quartzite, 
occasionally  alternating  with  greenish  talcose  schists,  and  en- 
closing veins  and  masses  of  anhydrite.  A  considerable  break 
occurs  in  the  series  of  specimens  above  this,  but  for  the  distance 
of  1,707  metres  from  the  northern  entrance  to  the  tunnel, 
corresponding  to  a  vertical  thickness  of  1,024  metres,  we  havej 
principally  sandstones,  conglomerates,  and  argillites,  occasionally 
with  anthracite.  The  serpentines  and  euphotides  which  ap- 
pear among  the  crystalline  schists  at  Bramant,  near  the  line  of 
the  tunnel,  were  not  met  with,  nor  was  the  underlying  gneiss 
encountered.  The  work  terminated  at  Bardonecchia  among  the 
crystalline  limestones. 

According  to  Sismonda  and  Elie  de  Beaumont,  there  is 
throughout  this  entire  section  no  evidence  of  inversion,  dislo- 
cation, or  repetition  in  the  series  of  7,000  metres  of  strata,  a 
conclusion  which  they  support  by  very  cogent  arguments. 
Lory,  on  the  contrary,  while  he  agrees  with  the  observers  just 
mentioned  in  looking  upon  the  crystalline  strata  as  altered 
mesozoic,  conceives  them  to  include  both  trias  and  lias,  and  to 
be  placed  beneath  the  true  carboniferous  by  a  great  inversion 
of  the  whole  succession.  This  series  of  crystalline  rocks  is 


336          THE  GEOLOGY  OF  THE  ALPS.          [XIV. 

very  conspicuous  along  the  southeast  side  of  Mont  Blanc,  ex- 
tending into  the  Valais,  and  is  regarded  by  Lory  as  a  peculiar 
modification  of  the  trias  and  lias,  so  enormously  thickened  and 
so  profoundly  altered  as  to  be  very  unlike  these  formations  to 
the  northwest  of  Mont  Blanc.  In  this  view  he  is  followed  by 
Favre  (§§  666,  753).  The  serpentines  and  related  rocks  of 
this  series  are  by  De  Beaumont,  Sismonda,  and  Lory  considered 
to  be  eruptive.  The  latter  speaks  of  these  as  eruptions  con- 
temporaneous with  the  deposition  of  the  strata,  probably  ac- 
companied by  emanations  which  effected  the  alteration  of  the 
sediments.  According  to  Favre,  they  are  clearly  interstratified 
with  the  lustrous  argillo-talcose  schists,  micaceous  limestones  and 
quartzites  of  the  great  series,  and  are  by  him  placed  in  the  trias. 
He  has  particularly  described  those  of  Mont  Joret  and  those  of 
the  Yal  de  Bruglie,  near  the  Petit  St.  Bernard,  where  they  are 
immediately  interstratified  with  greenish  schists,  and  associated 
with  steatite,  hornblendic  and  gneissic  strata.  The  serpentines 
of  Taninge  in  the  Chablais,  to  the  northwest  of  Mont  Blanc, 
he  also  classes  with  these  in  the  trias.  The  conclusions  of  Lory 
and  Favre  as  to  the  geological  age  of  these  crystalline  schists 
and  limestones  appear  to  us  untenable  in  the  light  of  Sismon- 
da's  investigations.  If  we  admit  with  the  latter  that  the  whole 
section  of  the  tunnel  represents  an  uninverted  series,  and  with 
Favre  that  its  uppermost  and  uncrystalline  portion  at  Modano 
is  truly  of  carboniferous  age,  it  is  clear  that  the  great  mass  of 
crystalline  schists  which  underlie  the  latter  should  correspond 
more  or  less  completely  to  the  pre-carboniferous  crystalline  strata 
to  the  northwest  of  Mont  Blanc.  Among  these  latter,  in  fact, 
as  observed  by  Favre,  there  occur  at  Col  Joli  and  Taninge  crys- 
talline limestones  and  talcose  schists  like  those  of  Maurienne. 
According  to  this  view,  which  harmonizes  the  conflicting  opin- 
ions, and  makes  the  crystalline  schists  and  limestones  of  the 
southeast  pre-carboniferous,  the  anhydrites,  with  limestones, 
talcose  slates,  and  quartzites  seen  in  the  Mont  Cenis  tunnel,  are 
not  the  equivalents  of  the  gypsum  and  cargneule  of  the  trias, 
but  may  correspond  to  the  anhydrites  which,  with  gypsum, 
dolomite,  serpentine  and  chloritic  slate,  are  met  with  in  the 
primitive  schists  of  Fahlun  in  Sweden. 


XIV.]  THE  GEOLOGY   OF  THE  ALPS.  337 

The  existence  of  great  and  perplexing  inversions  of  strata  in 
many  parts  of  the  Alps  is  well  known.  One  of  the  most  strik- 
ing cases  is  that  figured  by  Murchison  in  his  remarkable  paper 
on  the  geology  of  the  Alps  in  1848  (Quar.  Jour.  Geol.  Soc.,  V. 
246),  as  occurring  at  the  pass  of  Martinsloch  in  the  canton  of 
Glarus,  8,000  feet  above  the  sea.  Here  nummulitic  beds,  dip- 
ping S.  S.  E.  at  a  high  angle,  are  regurlaly  overlaid  by  the 
succeeding  sandstone  (flysch),  resting  unconformably  and  in  a 
nearly  horizontal  attitude  upon  the  edges  of  which  are  150  feet 
of  hard  Jurassic  limestone,  overlaid  in  its  turn  by  talcose  and 
micaceous  schists,  which  are  by  Escher  regarded  as  similar  to 
those  which  underlie  these  limestones  in  the  valley  below. 
This  mass  of  flysch  appeal's  near  by  to  dip  beneath  these  lime- 
stones, which,  in  their  turn,  are  regularly  overlaid  by  neocomian 
and  cretaceous  strata.  This  remarkable  superposition  of  sec- 
ondary and  older  crystalline  rocks  to  tertiary  is  explained  by 
Murchison,  in  accordance  with  the  suggestion  of  H.  D.  Eogers, 
as  the  probable  result  of  fracture  and  displacement  along  an 
anticlinal.  Many  striking  examples  of  inversion  are  described 
by  Favre  in  the  vicinity  of  Mont  Blanc.  The  mountain  of  the 
Voirons,  near  Geneva,  shows  at  its  base  tertiary  overlaid  by 
cretaceous  rocks,  upon  which  Jurassic  strata  are  superimposed. 
Similar  phenomena  are  met  with  along  the  north'  side  of  the 
Alps  from  Geneva  to  Austria,  and  at  various  localities  on  the 
southern  side,  in  Lombardy.  This  inversion,  %  moreover,  is  by 
no  means  confined  to  secondary  and  tertiary  strata.  In  the  val- 
ley of  Chamonix  the  secondary  limestones  dip  at  a  high  angle 
toward  Mont  Blanc,  and  plunge  beneath  its  crystalline  schists. 
Other  examples  of  the  superposition  of  crystalline  schists  to  the 
fossiliferous  sediments  have  been  pointed  out  by  EHe  de  Beau- 
mont in  the  mountains  of  Oisans,  and  confirmed  by  Lory  and 
Dausse,  while  similar  cases  have  been  recognized  by  Morlot 
and  Von  Hauer  in  the  eastern  Alps,  and  by  Eamond,De  Bouche- 
porn,  and  others  in  the  Pyrenees.  All  of  these  cases  are  by 
Favre  regarded  as  examples  of  the  same  process  of  inversion 
already  noticed  in  so  many  instances  among  the  secondary  and 
tertiary  strata  of  the  region.  He  proceeds  to  contrast  these 
15  v 


338  THE   GEOLOGY   OF  THE   ALPS.  [XIV. 

examples  with  that  of  the  gneisses  with  chloritic  and  micaceous 
schists,  which  in  western  Scotland,  according  to  Murchison, 
overlie  fossiliferous  Lower  Silurian  beds,  and  are  by  him  re- 
garded as  younger.  This,  upon  the  authority  of  Murchison, 
Favre  regards  as  a  singular  and  anomalous  fact.  It  should, 
however,  be  said  that  this  view  of  Murchison  is  rejected  by 
Nicoll,  who  explains  the  appearances  as  the  result  of  disloca- 
tion and  oversliding  of  older  crystalline  schists  upon  the  newer 
fossiliferous  beds,  in  which  case  the  western  Highlands  will 
form  no  exception  to  the  general  law  of  similar  appearances  in 
the  Alps  and  Pyrenees.  (Ante,  page  271.) 

The  fact  that  the  Jurassic  rocks  in  the  valley  of  Chamonix 
pass  beneath  the  crystalline  schists  of  Mont  Blanc  was  first  no- 
ticed by  De  Saussure,  and  was  afterwards  observed  by  Bergmann 
and  by  Bertrand,  who  argued  from  this  that  the  limestones  were 
older  than  the  gneiss.  Bertrand's  paper,  as  noticed  by  Favre, 
occurs  in  the  Journal  des  Mines,  VII.  376  (1797-1798). 
Later,  in  1824,  we  find  Keferstein  inquiring  whether  these 
overlying  gneisses  and  protogines  might  not  be  altered  flysch 
(that  is,  eocene),  a  view  which  he  subsequently  maintained. 
Similar  views  have  found  favor  among  later  geologists  ;  we  find 
Murchison  asserting  the  eocene  age  of  certain  Alpine  gneisses, 
mica-schists,  and  granites  ;  while  Lyell  has  suggested  that  the 
protogines,  gneisses,  etc.,  of  the  Alps  may  have  resulted  from 
the  alteration  both  of  secondary  and  tertiaiy  strata.  (Anniver- 
sary Address  to  the  Geological  Society,  1850.)  Studer  has 
taught  that  the  flysch  of  the  Grisons  has  been  changed  into 
crystalline  gneiss,  while  Rozet  and  Fournet,  with  Lory  and  Sis- 
monda,  have  assigned  to  the  Jurassic  period  the  great  system  of 
gneisses,  with  talcose  and  micaceous  schists,  which  make  up 
Monts  Cenis  and  Pelvoux,  and  much  of  the  mountains  on  the 
frontier  of  Piedmont  and  in  the  Valais. 

Hutton,  as  early  as  1 788,  had  taught  that  what  he  called  the 
primary  schists  were  sediments,  the  ruins  of  earlier  rocks  altered 
by  heat,  but  it  does  not  appear  that  he  attempted  to  fix  the 
relative  age  of  any  such  altered  rocks.  In  fact,  the  notion  of 
geological  periods,  based  upon  the  study  of  fossils,  was  not  as 


XIV.]  THE   GEOLOGY  OF  THE  ALPS.  339 

yet  fully  recognized.  The  suggestions  of  Bergmann  and  Ber- 
trand,  that  the  crystalline  rocks  of  the  Alps  are  newer  than  the 
fossiliferous  limestones  which  pass  beneath  them,  seems  to  have 
been  the  first  attempt  to  give  to  Hutton's  view  a  definite  and 
special  application,  and  the  inception  of  that  hypothesis  with 
which  we  have  since  become  familiar,  which  supposes  the  con- 
version of  mountain  masses  of  palaeozoic,  mesozoic,  and  even 
cenozoic  sediments,  in  the  Alps  and  elsewhere,  into  gneisses  and 
other  crystalline  rocks.*  Numerous  sections  in  the  vicinity  of 
Mont  Blanc  show  the  sedimentary  strata  in  their  normal  atti- 
tude, resting  unconformably  upon  the  crystalline  schists,  while 
in  some  localities  the  whole  succession  from  the  carboniferous 
to  the  eocene,  both  inclusive,  is  met  with.  In  many  parts, 
however,  the  carboniferous  is  wanting,  and  the  trias  forms  the 
base  of  the  column,  while  elsewhere  the  infra-liassic  beds  re- 
pose on  the  crystalline  schists,  and  in  the  Bernese  Alps  no 
fossiliferous  beds  lower  than  the  oolite  are  observed.  These 
variations  would  appear  to  be  connected  with  the  movement  of 
subsidence  which  permitted  the  deposition  of  marine  limestones 
above  the  carboniferous  strata ;  and  Favre  has  further  pointed 
out,  in  the  vicinity  of  Dorenaz,  a  want  of  conformity  between 
these  and  the  succeeding  formations. 

To  the  carboniferous  belongs  the  well-known  conglomerate 
of  Yalorsine,  which  includes  pebbles  of  gneiss,  quartzite,  talcose, 
and  micaceous  schist,  and  of  quartz  veins  with  tourmaline.  The 
paste,  which  is.  reddish,  talcose,  and  micaceous,  seems  identical 
with  many  of  the  pebbles,  so  that  it  is  sometimes  difficult  to 
distinguish  these  from  the  matrix.  A  thin  fibrous  envelope 
often  surrounds  the  pebbles  (§521).  Although  the  alternation 
of  these  beds  with  others  holding  plants  shows  them  to  be  of 
carboniferous  age,  it  is  often,  says  Favre,  difficult  to  fix  the 
lower  limit  of  this  formation,  on  account  of  the  great  resem- 
blance between  certain  of  the  carboniferous  sandstones  and 

[*  Already,  before  Hutton,  Von  Trebra,  in  1785,  had  taught  a  somewhat  similar 
doctrine.  He  supposed  that  a  slow  change  under  the  influence  of  heat  and  water, 
which  he  compared  to  a  fermentation,  is  constantly  going  on  in  the  interior 
of  the  rocks,  and  may  in  time  convert  mountains  of  granite  into  gneiss,  and  of 
gray  wacke  into  clay-slate.  (Erfahrungen  von  Innern  der  Gebirge,  page  48. )] 


340  THE   GEOLOGY   OF   THE  ALPS.  [XIV. 

portions  of  the  older  crystalline  schists,  which,  in  cases  where 
the  former  are  destitute  of  pebbles,  makes  it  impossible  to  dis- 
tinguish between  the  two.  Necker,  in  like  manner,  asserted 
that  it  was  impossible  to  draw  a  line  of  demarcation,  and  was 
hence  led  to  assert  a  passage  from  the  one  to  the  other.  The 
same  close  resemblance  was  noticed  by  De  Saussure,  and  is  testi- 
fied to  by  De  Mortillet  and  by  Sismonda,  who  says  of  the  feld- 
spathic  sandstone  (gres)  near  St.  Jean  in  Maurienne,  that  "  un- 
less we  take  care  we  run  the  risk  of  being  deceived,  and  of 
confounding  it  with  gneiss";  while  elsewhere  similar  rocks 
assume  the  aspect  of  granite  from  the  predominance  in  them  of 
feldspar.  Hence  it  has  happened  that  observers  like  Dolo- 
niieu  and  Bakewell  placed  the  anthracites  of  the  Alps  in  the 
mica-slate  formation,  and  that  Berger  described  as  a  "  veined 
granite  "  the  Aiguille  des  Posettes,  which,  according  to  Favre, 
consists  of  nearly  vertical  beds  of  carboniferous  sediments. 
In  illustration  of  this  condition  of  things,  Favre  cites  the 
observation  of  Boulanger,  according  to  whom  the  triassic  sand- 
stones of  the  department  of  Allier  are  made  up  of  quartz,  feld- 
spar, and  mica,  so  united  as  to  give  rise  to  a  sandstone  which 
would  be  taken  for  a  primitive  rock  but  for  the  occasional  pres- 
ence of  a  rolled  pebble  of  granite.*  The  paste  of  this  Valor- 
sine  conglomerate,  which  seems  identical  with  certain  of  the 
enclosed  pebbles,  appears,  according  to  Favre,  to  have  undergone 
a  certain  rearrangement,  so  that  the  beds  of  these  "  pretendus 
schists  cristallins  "  of  the  carboniferous  are  with  difficulty  dis- 
tinguished from  the  "  vrais  schists  cristallins  "  upon  which  they 
rest  unconformably.  I  insist  the  more  upon  these  details,  be- 
cause in  the  earlier  notice  of  Favre's  investigations  I  erroneously 
represented  him  as  including  in  the  carboniferous  a  great  mass 
of  the  older  crystalline  schists. 

In  this  connection  we  may  cite  the  observation  of  Sedgwick, 
who  cites  similar  cases  of  recomposed  rocks  in  Scotland,  "  which 
it  is  not  always  possible  to  distinguish  from  the  parent  rock," 
and  remarks  that  "  a  mechanical  rock  may  appear  highly  crys- 

*  See  Favre,  Terrains  liassique  et  keuperien,  etc.  (1859),  pp.  78,  79,  to 
which,  in  this  work,  he  refers  the  reader  for  further  explanation  on  this  point. 


XIV.]  THE   GEOLOGY   OF  THE  ALPS.  341 

talline  because  it  is  composed  of  crystalline  parts  derived 
from  some  pre-existing  crystalline  rock."  *  Emmons  also  has 
called  attention  to  the  existence  of  secondary  or  recomposed 
beds  of  talcose,  chloritic,  and  micaceous  schists  in  the  Taconic 
hills  of  western  New  England,  which,  according  to  him,  have 
been  confounded  with  the  older  parent  rocks.  (Ante,  page  251.) 
It  would  hardly  seem  necessary  to  call  attention  to  facts  which 
are  familiar  to  all  field-geologists  who  have  worked  much  among 
newer  deposits  in  the  vicinity  of  older  crystalline  rocks,  were 
it  not  that  their  significance  is  so  great  in  connection  with 
Alpine  geology. 

This  deceptive  resemblance  to  the  older  crystalline  rocks  in 
the  Alps,  as  might  be  supposed,  is  not  confined  to  the  carbonif- 
erous. Similar  cases  are  noticed  by  Favre  in  the  trias,  while 
at  the  Cols  du  Bonhomme  and  des  Fours  are  crystalline  aggre- 
gates also  noticed  by  Saussure  as  closely  resembling  the  older 
crystalline  rocks,  which  are  shown  by  the  fossils  of  interstrati- 
fied  beds  to  be  of  infra-liassic  age.  Studer,  in  opposition  to 
Murchison,  maintained  that  the  apparently  granitic  layers  in 
the  flysch  (eocene)  near  Interlaken  are  but  the  debris  of  an 
older  crystalline  rock,  while  the  crystalline  schists  of  the  Bolghen 
mountain  in  the  eastern  Alps,  supposed  by  Murchison  to  be  in 
some  way  interposed  in  the  flysch,  are  both  by  Studer  and  by 
Boue  regarded  as  merely  masses  of  the  older  crystalline  rocks 
in  a  tertiary  conglomerate. t 

In  discussing  the  age  of  the  "  true  crystalline  schists  "  of  the 
Alps,  to  make  use  of  his  expression  already  quoted,  Favre,  as 
we  have  seen,  places  them  beneath  the  carboniferous,  and  in 
opposition  to  the  suggestion  of  Murchison  and  the  opinion  of 
Gueymard,  that  they  may  be  of  Cambrian  and  Silurian  age, 
concludes  that  we  have  no  proof  of  the  existence  of  representa- 
tives of  these  systems  in  the  western  Alps  (§  808).  In  this 
connection  we  may  note  with  Favre  the  presence  at  Dienten,  in 
the  Tyrol,  of  a  Silurian  fauna,  intercalated  in  beds  of  gray  and 
green  chloritic  schists  (§697  b).  The  gneiss  of  Mettenbach, 

*  Geol.  Transactions  (1835),  III.  479. 
t  Ibid.,  III.  334 ;  GeoL  Jour.,  V.  210. 


342          THE  GEOLOGY  OF  THE  ALPS.          [XIV. 

near  the  Jungfrau,  has  afforded  to  Favre  a  pale  green  ophicalce 
resembling  that  of  the  Laurentian,  in  which  he  has  detected 
Uozoon  Canadense  (§697  a).  Having  thus  declared  his  convic- 
tion of  the  great  antiquity  of  the  crystalline  schists,  whose 
ruins  enter  into  the  composition  of  the  conglomerate  of  Valor- 
sine,  he  proceeds  to  remark  that  "  the  part  played  by  the  Alps 
of  Savoy  by  that  mysterious  force  called  metamorphism,  to 
which  the  formation  of  the  crystalline  schists  is  often  attributed, 
has  been  greatly  exaggerated."  He  adds,  "  I  have  always  been 
surprised  to  find  in  the  Alps  so  few  traces  of  this  pretended 
action,"  and  suggests  that  the  question  has  been  complicated  by 
the  resemblances  already  noted  between  the  crystalline  schists 
and  the  recomposed  rocks  of  the  coal  measures  (§  697  c).  In 
the  same  spirit  he  declared  in  1859  that  there  are  "scarcely 
any  evidences  of  alteration  after  the  Valorsine  conglomerate  " ; 
in  the  paste  of  which  he  admits  a  crystalline  rearrangement,  by 
no  means  improbable.*  It  appears  inconsistent  with  these 
expressions  of  opinion  to  find  our  author  admitting  with  Lory 
the  triassic  and  Jurassic  age  of  the  great  mass  of  lustrous  schists 
and  micaceous  limestones  which  are  overlaid  by  the  carbonifer- 
ous at  Modane,  and  at  various  localities,  as  we  have  seen,  in- 
clude serpentines,  steatites,  etc.  Our  author  feels  this  to  be  a 
difficulty,  and  speaks  of  these  serpentines,  unlike  those  of  the 
Montanvert,  the  Aiguilles  Rouges,  etc.,  as  belonging  to  non- 
crystalline  formations,  a  character  which  can  hardly  be  ascribed 
to  them.  If,  however,  Sismonda  be  correct  in  placing  them 
below  rocks  which  are,  according  to  Favre,  true  coal  measures, 
these  serpentines  and  steatites,  with  their  accompanying  schists 
and  limestones,  are,  as  we  have  already  shown,  in  the  same 
horizon  with  the  crystalline  schists  to  the  north  of  Mont  Blanc. 
The  origin  of  the  fan-like  structure  attributed  to  the  Alps 
by  nearly  all  observers  since  the  time  of  De  Saussure,  and  cor- 
rectly represented  in  the  sections  published  by  Studer  in  1851, 
and  by  Favre  in  1859,  is  explained  by  the  latter  in  accordance 
with  the  view  put  forward  by  Lory  in  1860.t  He  supposes 

*  Terrains  liassique  et  keuperien,  page  77. 

t  Lory,  Description  geologique  du  Dauphind,  p.  180. 


XIV.]  THE   GEOLOGY   OF  THE   ALPS.  343 

that  the  underlying  crystalline  rocks,  forced  by  great  lateral 
pressure,  formed  an  elevated  anticlinal  arch,  which,  breaking  on 
the  crown,  from  the  excess  of  curvature,  shows  the  lowest  rocks 
in  the  centre  of  the  rupture,  flanked  on  either  side  by  the  over- 
lying strata.  These,  in  their  upper  part,  are  subjected  to  a 
comparatively  feeble  lateral  pressure,  while  the  deeper  portions 
are  forcibly  compressec^  by  the  smaller  folds  on  either  side,  from 
which  results  the  fan-like  or  sheaf-like  structure  of  the  mass. 
The  newer  strata  in  the  synclinals  are  by  this  process  arranged 
in  troughs,  and  are  more  or  less  overlaid  by  the  older  rocks. 
Such  a  synclinal  exists  in  the  valley  of  Chamonix,  between 
the  two  ruptured  and  eroded  anticlinals  represented  by  Mont 
Blanc  and  the  Brevent.  In  illustration  of  this  structure  Favre 
has  given  a  grand  section  commencing  to  the  northwest  in  the 
mountain  known  as  Les  Fiz,  which,  overlooking  the  Col  d'An- 
terne,  rises  to  a  height  of  3,180  metres,  and  displays  all  the 
Alpine  formations  from  the  sandstones  of  Taviglionaz,  overlying 
the  nummulitic  beds,  down  to  the  carboniferous,  which  is  seen 
resting  on  the  crystalline  schists.  These  appear  in  the  height 
of  Pormenaz,  and  in  the  Brevent,  at  the  northwest  base  of 
which  the  carboniferous  rocks  are  arranged  in  a  sharp  fold  dip- 
ping beneath  the  crystalline  strata.  The  latter,  to  the  northeast, 
rise  in  the  Aiguilles  Rouges,  which  are  steep  hills  of  vertical 
beds  including  hornblendic,  chloritic,  and  talcose  rocks,  with 
petrosilex,  eclogite,  and  serpentine.  The  highest  of  the  Ai- 
guilles rises  2,944  metres  above  the  sea,  and  consequently  1,892 
metres  above  the  valley  of  Chamonix.  This  summit,  which 
was  visited  by  Favre,  was  found  to  be  capped  by  horizontal 
strata,  consisting  at  the  top  of  about  thirty-seven  metres  of  Ju- 
rassic beds,  with  belemnites  and  ammonites,  underlaid  by  infra- 
liassic  strata  with  cargneules,  sandstones,  and  schists,  the  whole 
resting  upon  vertical  strata  of  unctuous  mica- schists,  which 
enclosed  a  bed  of  saccharoidal  limestone.  From  thence  we  pass 
over  the  valley  of  Chamonix,  which  holds  enfolded  in  crys- 
talline schists  triassic  and  Jurassic  strata,  and  over  the  summit 
of  Mont  Blanc,  to  find  the  same  folding:  repeated  between  the 
base  of  the  latter  and  the  protogines  of  Mont  Chetif.  The  fan- 


344  THE   GEOLOGY  OF  THE  ALPS.  [XIV. 

like  structure  attributed  to  this  last  is  questioned  by  Lory, 
according  to  whom  the  strata  of  this  mountain  dip  uniformly 
to  the  southeast,  and  are  overlaid  by  the  great  mass  of  crystal- 
line talcose  schists  and  micaceous  limestones  assigned  by  him 
to  the  trias  ;  but  apparently,  as  we  have  endeavored  to  show, 
a  portion  of  the  pre -carboniferous  crystalline  schists.  These 
rocks  are  well  displayed  further  on  int-the  mountain  of  Cra- 
moiit,  and  are  regarded  by  Favre  as  identical  with  those  of 
Mont  Cenis.*  Lory  conceives  that  the  attitude  of  the  rocks  of 
Mont  Chetif  to  the  Jurassic  strata  in  the  trough  at  the  southeast 
base  of  Mont  Blanc  is  due  to  a  great  fault  with  an  uplift,  which 
has  brought  these  older  rocks  to  overlie  the  Jurassic  beds. 

With  the  facts  before  us,  we  can  with  Favre  trace  the  history 
of  Mont  Blanc  from  the  time  when  over  a  partially  submerged 
region  of  gneiss  and  crystalline  schists  the  carboniferous  strata 
with  their  beds  of  coal  and  their  plant-remains  were  being  de- 
posited j  many  of  the  strata  being  made  up  from  the  partially 
disintegrated  crystalline  schists  and  now  scarcely  distinguish- 
able from  them.  After  some  disturbance,  the  secondary  forma- 
tions were  laid  down  unconformably  alike  over  the  carbonifer- 
ous and  the  older  strata,  followed  by  the  nummulitic  beds  and 
their  overlying  sandstones ;  the  whole,  from  the  base  of  the 
trias,  having  in  this  region  an  aggregate  thickness  of  about 
1,250  metres.  Subsequently  to  this  occurred  the  great  move- 
ments which  threw  into  folds  all  of  these  strata,  enclosing,  as 
in  the  Tarentaise,  the  nummulites,  with  Jurassic  and  carbonifer- 
ous fossils,  among  the  folds  of  the  crystalline  schists.  This 
was  followed  by  great  denudation,  which  removed  from  the 
broken  anticlinals  the  secondary  rocks,  leaving,  however,  in  the 
horizontal  Jurassic  beds  which  still  cap  the  Aiguilles  Rouges, 
an  evidence  of  the  former  spread  of  these  formations,  which 
once  extended  over  what  is  now  the  summit  of  Mont  Blanc. 
It  is  worthy  of  note  that  the  highest  portions  of  this  latter  do 
not  exhibit  the  underlying  gneiss,  but  are  capped  by  crystalline 
schists,  which  may  be  supposed  to  rest  upon  it,  as  do  the  sec- 

*  See  in  this    connection  Hebert,  Bull.  Soc.  Geol.  de  France  (2),  XXV. 
356. 


XIV.]  THE  GEOLOGY  OF  THE  ALPS.  345 

ondary  strata  upon  the  schists  of  the  Aiguilles  Rouges.  These 
elevated  points  are  evidences  of  the  enormous  erosion  in  this 
region,  the  results  of  which  have  contributed  to  build  up  in  the 
lower  regions  of  the  Alps,  and  in  the  Jura,  the  great  masses  of 
miocene  sediment  known  as  the  molasse,  —  a  formation  partly 
marine  and  partly  lacustrine,  which  attains  in  some  parts  a 
thickness  of  more  than  2,000  metres.  This  period  was  fol- 
lowed by  other  movements  which  have  raised  the  beds  of 
molasse  to  a  vertical  attitude,  and  in  some  cases  inverted  them, 
so  that  they  appear  dipping  beneath  the  nummulitic  formation. 
It  is  worthy  of  note  that  the  molasse  near  Geneva  includes  in 
its  upper  part  a  lacustrine  limestone,  followed  by  marls  with 
gypsum,  and  by  lignites. 

That  the  nature  of  the  fan-like  structure  of  the  Alps  is  cor- 
rectly represented  in  the  sections  of  Studer,  Lory,  and  Favre, 
can,  we  think,  no  longer  admit  of  doubt.  Another  explana- 
tion was,  however,  possible ;  the  dipping  of  the  beds  on  either 
side  toward  the  centre  of  the  mass  might  indicate  synclinal 
mountains,  lying  between  two  eroded  anticlinals.  Such  a 
mountain- structure  appears  not  to  be  uncommon  in  regions 
where  the  undulations  are  moderate ;  and  is,  according  to  Les- 
ley, frequent  in  the  anthracite  region  of  Pennsylvania.  Snow- 
don  in  Wales,  according  to  Sedgwick,  and  Ben  Nevis  and  Ben 
Lawers  in  the  Scottish  Highlands,  according  to  Murchison,  are 
also  examples  of  this  structure,  the  summits  of  all  of  these 
being  composed  of  newer  strata,  beneath  which,  on  either  side, 
dip  the  older  formations.  When,  therefore,  geologists  of  au- 
thority from  Bertrand  and  Keferstein  to  Murchison  and  Lyell 
maintained  that  the  crystalline  rocks  of  Mont  Blanc  were 
newer  than  the  limestones  of  the  valleys  on  either  side,  and 
even  declared  them  to  be  altered  sediments  of  the  tertiary 
period,  it  was  difficult  to  regard  Mont  Blanc  as  anything  else 
than  a  synclinal  mountain  similar  in  general  structure  and 
origin  to  those  just  mentioned.  Hence  it  was  that  in  1860 
(American  Journal  of  Science  (2),  XXIX.  118)  I  remarked, 
"  the  weight  of  evidence  now  tends  to  show  that  the  crystal- 
line nucleus  of  the  Alps,  so  far  from  being  an  extruded  mass 
15* 


346          THE  GEOLOGY  OF  THE  ALPS.         [XIV. 

of  so-called  primitive  rock,  is  really  an  altered  sedimentary 
deposit  more  recent  than  many  of  the  fossiliferous  strata  upon 
their  flanks,  so  that  the  Alps,  as  a  whole,  have  a  general  syn- 
clinal structure."  This  view  of  the  recent  age  of  the  crystal- 
line rocks  of  this  region,  supported  though  it  has  been  by  the 
authority  of  great  names,  must  now,  we  conceive,  be  abandoned, 
and  their  great  antiquity,  as  maintained  by  the  learned  pro- 
fessor of  Geneva,  admitted.  It  however  remains  true  that  the 
extrusion  and  laying  bare  of  these  ancient  crystalline  rocks  is, 
as  we  have  seen,  an  event  geologically  very  recent. 

It  would  greatly  exceed  our  present  limits  to  notice  our  au- 
thor's learned  discussion  of  the  superficial  geology,  including 
the  glacial  phenomena,  of  the  Alpine  region,  His  views  upon 
some  of  the  most  keenly  controverted  questions  with  regard  to 
glacial  action  will  be  found  set  forth  in  his  letter  to  Sir  R.  I. 
Murchison  on  the  Origin  of  Alpine  Lakes  and  Valleys,  which 
appeared  in  the  London,  Edinburgh,  and  Dublin  Philosophical 
Magazine  for  March,  1865. 

This  beautiful  work  of  Professor  Favre  is  accompanied  by 
an  atlas  of  thirty-two  folio  plates,  embracing  maps,  sections, 
views,  and  figures  of  organic  remains,  which  elucidate  the  text 
in  a  very  complete  manner.  It  is  a  magnificent  monument  to 
the  industry,  acumen,  and  scientific  zeal  of  one  who  for  a  quar- 
ter of  a  century  has  devoted  his  time  and  his  fortune  to  the 
pursuit  of  science,  and  has  worthily  completed  the  task  which 
his  illustrious  countryman  De  Saussure  commenced. 


XIV.]          THE  GEOLOGY  OF  THE  ALPS.          347 


APPENDIX. 


[THE  crystalline  rocks  in  the  line  of  the  Mont  Cenis  Tunnel,  con- 
sisting of  micaceous  limestones,  dolomites,  gypsums,  and  anhydrites, 
with  talcose  schists,  serpentines,  and  quartzite,  have  been,  as  we 
have  seen,  regarded  by  all  observers  as  altered  mesozoic  strata. 
According  to  Elie  de  Beaumont  and  Sismonda,  they  are  metamor- 
phosed Jurassic,  and  the  un crystalline  anthraciferous  strata  in  con- 
tact with  them  near  Modane  are  unaltered  rocks  belonging  to  the 
same  period.  Favre,  on  the  other  hand,  while  maintaining  the  car- 
boniferous age  of  the  latter,  followed  Lory  in  regarding  the  crystal- 
line strata  as  more  recent  than  these,  and,  in  fact,  as  metamorphosed 
triassic.  These  conclusions  as  to  the  age  of  the  crystalline  rocks  I 
have  ventured  in  the  preceding  pages  to  call  in  question,  and  have 
compared  them  with  certain  ancient  crystalline  schists  of  Scandi- 
navia. A  letter  from  Professor  Favre,  dated  February,  1872,  admits 
the  justice  of  my  strictures  ;  he  now  rejects  the  notion  that  they 
are  altered  fossiliferous  strata,  and  regards  them  as  of  unknown  age, 
citing  the  recently  expressed  opinion  of  Gastaldi  that  they  are  older 
than  the  carboniferous  and  are  altered  palaeozoic.  The  existence 
of  such  rocks  of  palaeozoic  age  is,  however,  improbable,  and  those 
to  which  I  have  compared  them  are  eozoic. 

Professor  Favre  writes,  with  reference  to  my  ideas  as  expressed  in 
the  above  review  and  also  in  my  address  at  Indianapolis  (ante,  pages 
286-312),  as  to  the  possible  alteration  of  palaeozoic  and  more  re- 
cent strata  to  crystalline  schists  :  "  Je  vois  avec  grand  plaisir  que 
vous  n'y  croyez  guere,  puisque  vous  ne  voyez  nulle  part  des  schistes 
cristallins  dont  on  puisse  dire  que  ce  sont  des  schistes  paleozoiques 
altered.  Je  suis  arrive  a  croire  qu'il  n'y  a  pas  de  metamorphisme 
pour  las  terrains  en  grand,  au  moins  bien  peu,  et  que  tous  les  ter- 
rains se  sont  deposes  a  peu  pres  dans  1'etat  oil  nous  les  voyons."* 

*  "  I  see  with  great  pleasure  that  you  have  little  belief  in  it "  (the  alteration 
of  palaeozoic  and  more  recent  strata  to  crystalline  schists),  "since  you  nowhere 
recognize  crystalline  schists  of  which  it  can  be  said  that  they  are  altered 
palaeozoic  schists.  I  have  come  to  believe  that  there  is  little  or  no  metamor- 
phisra  for  the  great  formations,  and  that  all  these  formations  were  deposited 
very  nearly  in  the  state  in  which  we  see  them."  With  the  above  extract  from 


348  THE   GEOLOGY   OF  THE  ALPS.  [XIV. 

He  then  proceeds  to  explain  his  view  that  the  crystalline  schists, 
the  dolomites,  and  the  serpentines  have  been  deposited  as  such,  or 
have  only  undergone  a  subsequent  molecular  change,  such  as  I  have 
described  on  pages  300  and  305  of  the  present  volume.  It  is  grati- 
fying to  record  such  testimony  to  the  views  I  have  so  long  advo- 
cated, from  the  learned  geologist  of  Geneva,  who  has  devoted  his 
life  to  the  study  of  what  is  generally  regarded  as  the  classic  region 
of  rock-inetamorphism. 

The  dip  of  the  strata  of  the  whole  section  of  the  Mont  Cenis  Tun- 
nel is,  according  to  Sismonda  and  Elie  de  Beaumont,  to  the  north- 
west, but,  according  to  Favre  and  to  Fillet,  the  carboniferous  rocks  at 
Modane  dip  to  the  southward,  suggesting  (what  might  here  be  looked 
for),  a  want  of  conformity  between  the  crystalline  and  uncrystal- 
line  series.  The  ancient  views  of  Elie  de  Beaumont  and  of  Sismonda, 
according  to  whom  the  anthraciferous  rocks  of  this  region  belong  to 
a  single  great  series  of  Jurassic  age,  which  includes  at  the  same  time 
crystalline  schists,  a  carboniferous  flora,  a  Jurassic  fauna,  and  num- 
mulitic  beds,  appear  to  be  still  maintained  by  these  geologists,  and 
are  set  forth  by  De  Beaumont  in  a  communication  to  the  French 
Academy  of  Science,  in  1871,  on  the  rocks  of  the  Mont  Cenis  Tun- 
nel. The  publication  of  this  in  the  Comptes  Eendus  called  forth 
an  energetic  protest  from  Fillet  in  behalf  of  the  Academy  of  Sci- 
ences of  Savoy,  in  December,  1871.  He  there  complains  of  the 
persistent  maintenance  of  views  which  he  declares  to  have  been  set 
aside  by  the  labors  of  Favre  and  others,  as  shown  in  the  work  re- 
viewed above,  and  adds :  "  The  opening  of  the  Mont  Cenis  Tunnel 
might  have  been  expected  to  put  an  end  to  the  discussion,  since  we 
see  at  St.  Andre,  near  Modane,  the  primitive  granitic  rock  overlaid 
by  the  coal  formation  with  anthracite,  by  the  trias,  and  by  the 
liassic  schists  with  belemnites,  all  placed  in  their  normal  order  and 
succession."] 

Favre's  letter  to  me,  written  in  February,  1872,  may  be  compared  Giimbel's 
conclusions,  cited  in  a  note  to  page  305,  from  his  letter  to  me,  also  written 
early  in  1872. 


XV. 


HISTORY   OF   THE    NAMES   CAMBRIAN 
AND   SILURIAN  IN   GEOLOGY. 

The  present  essay  appeared  in  the  Canadian  Naturalist  for  April  and  July,  1872,  and 
the  first  two  parts  of  it  were  reprinted  in  Nature  for  May  of  the  same  year,  and  sub- 
sequently in  the  Geological  Magazine  in  1873,  while  a  French  translation  of  the  entire 
paper  by  Dewalque,  with  notes  and  additions,  is  announced  as  about  to  appear  in 
Belgium. 

Having  been  desired,  in  1872,  to  prepare  for  publication  a  notice  of  the  scientific 
labors  of  Murchison,  it  became  necessary  for  me  to  examine  critically  the  whole  ground 
of  the  Cambrian  and  Silurian  controversy,  a  task  which  proved  much  more  serious  than 
I  had  supposed,  and  brought  to  light  facts  which  both  surprised  and  pained  me.  In 
the  interest  of  truth  I  determined  to  write  the  history  as  I  have  here  given  it,  and 
I  had  the  great  pleasure  of  laying  this  statement,  in  its  completed  form,  before  the 
venerable  Sedgwick,  who,  in  several  letters  written  to  me  during  the  last  months  of 
his  life,  testified  his  gratitude  for  the  manner  in  which  justice  had  at  length  been 
done  to  him  and  to  his  labors,  and,  moreover,  warmly  acknowledged  it  hi  the  Preface 
to  a  new  Catalogue  of  the  Cambridge  Fossils,  dictated  by  him  a  few  months  before 
his  death,  which  took  place  in  his  eighty-eighth  year,  at  Trinity  College,  Cambridge, 
January  27,  1873.  That  Preface  contains  a  more  circumstantial  and  complete  account 
of  the  personal  history  of  the  controversy  than  had  previously  appeared. 

Such  a  history  as  this  of  the  Cambrian  and  Silurian  rocks  of  the  Old  World  was  not 
complete  without  an  account  of  the  progress  of  our  knowledge  regarding  the  similar 
rocks  of  North  America  ;  and  I  have,  therefore,  in  the  third  part,  endeavored  to  set 
forth  in  an  impartial  manner  the  share  of  each  investigator  in  the  working  out  of  this 
important  chapter  in  the  geological  history  of  our  continent.  I  have,  in  the  present 
reprint,  made  several  important  additions,  and  some  changes  with  the  view  of  ren- 
dering more  complete,  both  for  Great  Britain  and  North  America,  the  history  of  these 
older  palaeozoic  rocks.  The  additions  and  the  important  changes,  whether  in  notes 
or  in  the  text,  are  distinguished  by  being  enclosed  in  brackets. 

IT  is  proposed  in  the  following  pages  to  give  a  concise  ac- 
count of  the  progress  of  investigation  of  the  lower  palaeozoic 
rocks  during  the  last  forty  years.  The  subject  may  naturally 
be  divided  into  three  parts :  1.  The  history  of  Silurian  and 
Upper  Cambrian  in  Great  Britain  from  1831  to  1854;  2. 
That  of  the  still  more  ancient  palaeozoic  rocks  in  Scandinavia, 
Bohemia,  and  Great  Britain  up  to  the  present  time,  including 
the  recognition  by  Barrande  of  the  so-called  primordial  palaeo- 


350  CAMBRIAN  AND   SILURIAN  IN   EUROPE.  [XV. 

zoic  fauna;  3.   The  history  of  the  lower  palaeozoic  rocks  of 
North  America. 

I.  SILURIAN  AND  UPPER  CAMBRIAN  IN  GREAT  BRITAIN. 

Less  than  forty  years  since,  the  various  uncrystalline  sedi- 
mentary rocks  beneath  the  coal-formation  in  Great  Britain  and 
in  continental  Europe  were  classed  together  under  the  common 
name  of  graywacke  or  grauwacke,  a  term  adopted  by  geologists 
from  German  miners,  and  originally  applied  to  sandstones  and 
other  coarse  sedimentary  deposits,  but  extended  so  as  to  include 
associated  argillites  and  limestones.  Some  progress  had  been 
made  in  the  study  of  this  great  Graywacke  formation,  as  it 
was  called,  and  organic  remains  had  been  described  from  vari- 
ous parts  of  it ;  but  to  two  British  geologists  was  reserved  the 
honor  of  bringing  order  out  of  this  hitherto  confused  group  of 
strata,  and  establishing  on  stratigraphical  and  palseontological 
grounds  a  succession  and  a  geological  nomenclature.  The 
work  of  these  two  investigators  was  begun  independently  and 
simultaneously  in  different  parts  of  Great  Britain.  In  1831 
and  1832,  Sedgwick,  aided  in  the  early  part  of  his  labors  by 
Mr.  Charles  Darwin,  made  a  careful  section  of  the  rocks  of 
North  Wales  from  the  Menai  Strait  across  the  range  of  Snow- 
don  to  the  Berwyn  hills,  thus  traversing  in  a  southeastern  di- 
rection Caernarvon,  Denbigh,  and  Merionethshire.  Already,  he 
tells  us,  he  had  in  1831  made  out  the  relations  of  the  Bangor 
group  (including  the  Llanberris  slates  and  the  overlying  Har- 
lech  grits),  and  showed  that  the  fossiliferous  strata  of  Snowdon 
occupy  a  synclinal,  and  are  stratigraphically  several  thousand 
feet  above  the  horizon  of  the  latter.  Following  up  this  investi- 
gation in  1832,  he  established  the  great  Merioneth  anticlinal, 
which  brings  up  the  lower  rocks  on  the  southeast  side  of  Snow- 
don, and  is  the  key  to  the  structure  of  North  Wales.  From 
these,  as  a  base,  he  constructed  a  section  along  the  line  already 
indicated,  over  Great  Arenig  to  the  Bala  limestone,  the  whole 
forming  an  ascending  series  of  enormous  thickness.  This 
limestone  in  the  Berwyn  hills  is  overlaid  by  many  thousand 
feet  of  strata  as  we  proceed  eastward  along  the  line  of  section, 


XV.]  CAMBRIAN  AND  SILURIAN  IN  EUROPE.  351 

until  at  length  the  eastern  dip  of  the  strata  is  exchanged  for  a 
westward  one,  thus  giving  to  the  Berwyn  chain,  like  that  of 
Snowdon,  a  synclinal  structure.  As  a  consequence  of  this,  the 
limestone  of  Bala  reappears  on  the  eastern  side  of  the  Berwyns, 
underlaid  as  before  by  a  descending  series  of  slates  and  por- 
phyries. These  results,  with  sections,  were  brought  before  the 
British  Association  for  the  Advancement  of  Science  at  its 
meeting  at  Oxford,  in  1832,  but  only  a  brief  and  imperfect 
account  of  the  communication  of  Sedgwick  on  this  occasion 
appears  in  the  Proceedings  of  the  Association.  He  did  not  at 
this  time  give  any  distinctive  name  to  the  series  of  rocks  in 
question.  (L.  E.  &  D.  Philos.  Mag.  [1854]  (4),  VIII.  495.) 

Meanwhile,  in  the  same  year,  1831,  Murchison  began  the 
examination  of  the  rocks  on  the  river  Wye,  along  the  southern 
border  of  Radnorshire.  In  the  next  four  years  he  extended 
his  researches  through  this  and  the  adjoining  counties  of  Here- 
ford and  Salop,  distinguishing  in  this  region  four  separate 
geological  formations,  each  characterized  by  peculiar  fossils. 
These  formations  were,  moreover,  traced  by  him  to  the  south- 
westward,  across  the  counties  of  Brecon  and  Caermarthen; 
thus  forming  a  belt  of  fossiliferous  rocks  stretching  from  near 
Shrewsbury  to  the  mouth  of  the  river  Towey,  a  distance  of 
about  one  hundred  miles  along  the  northwest  border  of  the 
great  Old  Red  sandstone  formation,  as  it  was  then  called,  of 
the  west  of  England. 

The  results  of  his  labors  among  the  rocks  of  this  region  for 
the  first  three  years  were  set  forth  by  Murchison  in  two  papers 
presented  by  him  to  the  Geological  Society  of  London  in  Janu- 
ary, 1834.  (Proc.  Geol.  Soc.,  II.  11.)  The  formations  were 
then  named  as  follows  in  descending  order :  1 .  Ludlow,  2. 
Wenlock ;  constituting  together  an  upper  group ;  3.  Caradoc, 
4.  Llandeilo  (or  Builth) ;  forming  a  lower  group.  The  Llan- 
deilo  formation,  according  to  him,  was  underlaid  by  what  he 
called  the  Longmynd  and  Gwastaden  rocks.  The  non-fossilif- 
erous  strata  of  the  Longmynd  hills  in  Shropshire  were  described 
as  rising  up  to  the  east  from  beneath  the  Llandeilo  rocks  ;  and  as 
appearing  again  in  South  Wales  at  the  same  geological  horizon, 


352  CAMBRIAN  AND   SILURIAN  IN  EUROPE.  IXV. 

at  Gwastaden  in  Breconshire,  and  to  the  west  of  Llandovery  in 
Caermarthenshire  ;  constituting  an  underlying  series  of  con- 
torted slaty  rocks  many  thousand  feet  in  thickness,  and  desti- 
tute of  organic  remains.  The  position  of  these  rocks  in  South 
Wales  was,  however,  to  the  northwest,  while  the  strata  of  the 
Longmynd,  as  we  have  seen,  appear  to  the  east  of  the  fossilif- 
erous  formations. 

In  the  L.  E.  &  D.  Philosophical  Magazine  for  July,  1835, 
Murchison  gave  to  the  four  formations  above  named  the  des- 
ignation of  Silurian,  in  allusion,  as  is  well  known,  to  the  an- 
cient British  tribe  of  the  Silures.  It  now  became  desirable  to 
find  a  suitable  name  for  the  great  inferior  series,  which,  accord- 
ing to  Murchison,  rose  from  beneath  his  lowest  Silurian  forma- 
tions to  the  northwest,  and  appeared  to  be  widely  spread  in 
Wales.  Knowing  that  Sedgwick  had  long  been  engaged  in 
the  s^udy  of  these  rocks,  Murchison,  as  he  tells  us,  urged  him 
to  give  them  a  British  geographical  name.  Sedgwick  accord- 
ingly proposed  for  this  great  series  of  Welsh  rocks  the  appro- 
priate designation  of  Cambrian,  which  was  at  once  adopted  by 
Murchison  for  the  strata  supposed  by  him  to  underlie  his  Silu- 
rian system.  (Murchison,  Anniv.  Address,  1842 ;  Proc.  Geol. 
Soc.,  III.  641.)  This  was  almost  simultaneous  with  the  giving 
of  the  name  of  Silurian,  for  in  August,  1835,  Sedgwick  and 
Murchison  made  communications  to  the  British  Association  at 
Dublin  on  Cambrian  and  Silurian  Eocks.  These,  in  the  vol- 
ume of  Proceedings  (pp.  59,  60),  appear  as  a  joint  paper, 
though  from  the  text  they  would  seem  to  have  been  separate. 
Sedgwick  then  described  the  Cambrian  rocks  of  North  Wales 
as  including  three  divisions  :  First,  the  Upper  Cambrian,  which 
occupies  the  greater  part  of  the  chain  of  the  Berwyns,  where, 
according  to  him,  it  was  connected  with  the  Llandeilo  forma- 
tion of  the  Silurian.  To  the  next  lower  division,  Sedgwick 
gave  the  name  of  Middle  Cambrian,  making  up  all  the  higher 
mountains  of  Caernarvon  and  Merionethshire,  and  including 
the  roofing-slates  and  flagstones  of  this  region.  This  middle 
group,  according  to  him,  afforded  a  few  organic  remains,  as  at 
the  top  of  Snowdon.  The  inferior  division,  designated  as 


XV.]  CAMBRIAN  AND  SILURIAN  IN  EUROPE.  353 

Lower  Cambrian,  included  the  crystalline  rocks  of  the  south- 
west coast  of  Caernarvon  and  a  considerable  portion  of  Angle- 
sea,  and  consisted  of  chloritic  and  micaceous  schists,  with  slaty 
quartzites  and  subordinate  beds  of  serpentine  and  granular 
limestone  ;  the  whole  without  organic  remains. 

These  crystalline  rocks  were,  however,  soon  afterwards  ex- 
cluded by  him  from  the  Cambrian  series,  for  in  1838  (Proc. 
Geol.  Soc.,  II.  679)  Sedgwick  describes  further  the  section 
from  the  Menai  Strait  to  the  Berwyns,  and  assigns  to  the 
chloritic  and  micaceous  schists  of  Anglesea  and  Caernarvon  a 
position  inferior  to  the  Cambrian,  which  he  divides  into  two 
parts ;  namely,  Lower  Cambrian,  comprehending  the  old  slate 
series,  up  to  the  Bala  limestone  beds  ;  and  Upper  Cambrian, 
including  the  Bala  beds,  and  the  strata  above  them  in  the  Ber- 
wyn  chain,  to  which  he  gave  the  name  of  the  Bala  group. 
The  dividing  line  between  the  two  portions  was  subsequently 
extended  downwards  by  Sedgwick  to  the  summit  of  the  Arenig 
slates  and  porphyries.  The  lower  division  was  afterwards  sub- 
divided by  him  into  the  Bangor  group  (to  which  the  name  of 
Lower  Cambrian  was  henceforth  to  be  restricted),  including  the 
Llanberris  roofing-slates  and  the  Harlech  grits  or  Barmouth 
sandstones ;  and  the  Festiniog  group,  which  included  the  Lin- 
gula  flags  and  the  succeeding  Tremadoc  slates. 

In  the  communication  of  Murchison  to  the  same  Dublin 
meeting,  in  August,  1835,  he  repeated  the  description  of  the 
four  formations  to  which  he  had  just  given  the  name  of  Si- 
lurian ;  which  were,  in  descending  order,  Ludlow  and  Wen- 
lock  (Upper  Silurian),  and  Caradoc  and  Llandeilo  (Lower  Si- 
lurian). The  latter  formation  was  then  declared  by  Murchison 
to  constitute  the  base  of  the  Silurian  system,  and  to  offer  in 
many  places  in  South  Wales  distinct  passages  to  the  underly- 
ing slaty  rocks,  which  latter  were,  according  to  him,  the  Upper 
Cambrian  of  Sedgwick. 

Meanwhile,  to  go  back  to  1834,  we  find  that  after  Murchi- 
son had,  in  his  communication  to  the  Geological  Society,  de- 
fined the  relation  of  his  Llandeilo  formation  to  the  underlying 
slaty  series,  but  before  the  names  of  Silurian  and  Cambrian 


354  CAMBRIAN  AND   SILURIAN  IN  EUROPE.  [XV. 

had  been  given  to  these  respectively,  Sedgwick  and  Murchison 
visited  together  the  principal  sections  of  these  rocks  from  Caer- 
marthenshire  to  Denbighshire.  The  greater  part  of  this  region 
was  then  unknown  to  Sedgwick,  but  had  been  already  studied 
by  Murchison,  who  interpreted  the  sections  to  his  companion 
in  conformity  with  the  scheme  already  given ;  according  to 
which  the  beds  of  the  Llandeilo  were  underlaid  by  the  slaty 
rocks  which  appear  along  their  northwestern  border.  When, 
however,  they  entered  the  region  which  had  already  been  ex- 
amined by  Sedgwick,  and  reached  the  section  on  the  east  side 
of  the  Berwyns,  the  fossiliferous  beds  of  Meifod  were  at  once 
pronounced  by  Murchison  to  be  typical  Caradoc,  while  others 
in  the  vicinity  were  regarded  as  Llandeilo.  The  beds  of  Mei- 
fod had,  on  palaeontological  grounds,  been  by  Sedgwick  identi- 
fied with  those  of  Glyn  Ceirog,  which  are  seen  to  be  immedi- 
ately overlaid  by  Wenlock  rocks.  These  determinations  of 
Murchison  were,  as  Sedgwick  tells  us,  accepted  by  him  with 
great  reluctance,  inasmuch  as  they  involved  the  upper  part  of 
his  Cambrian  section  in  most  perplexing  difficulties.  When 
however,  they  crossed  together  the  Berwyn  chain  to  Bala,  the 
limestones  in  this  locality  were  found  to  contain  fossils  nearly 
agreeing  with  those  of  the  so-called  Caradoc  of  Meifod.  The 
examination  of  the  section  here  presented  showed,  however, 
that  these  limestones  are  overlaid  by  a  series  of  several  thou- 
sand feet  of  strata,  bearing  no  resemblance  either  in  fossils  or 
in  physical  characters  to  the  Wenlock  formation,  which  over- 
lies the  Caradoc  beds  of  Glyn  Ceirog.  This  series,  was,  there- 
fore, by  Murchison  supposed  to  be  identical  with  the  rocks 
which,  in  South  Wales,  he  had  placed  beneath  the  Llandeilo, 
and  he  expressly  declared  that  the  Bala  group  could  not  be 
brought  within  the  limits  of  his  Silurian  system.  It  may  here 
be  added  that  in  1842  Sedgwick  re-examined  this  region, 
accompanied  by  that  skilled  paleontologist,  Salter,  confirming 
the  accuracy  of  his  former  sections,  and  showing,  moreover,  by 
the  evidence  of  fossils  that  the  beds  of  Meifod,  Glyn  Ceirog, 
and  Bala  are  very  nearly  on  one  parallel.  Yet,  with  the  evi- 
dence of  the  fossils  before  him,  Murchison,  in  1834,  placed 


XV.]  CAMBRIAN  AND  SILURIAN   IN  EUROPE.  355 

the  first  two  in  his  Silurian  system,  and  the  last  deep  down  in 
the  Upper  Cambrian;  and  consequently  was  aware  that  on 
pakeontological  grounds  it  was  impossible  to  separate  the  lower 
portion  of  Silurian  system  from  the  Upper  Cambrian  of  Sedg- 
wick.  (These  names  are  here  used  for  convenience,  although 
we  are  speaking  of  a  time  when  they  had  not  been  applied  to 
designate  the  rocks  in  question.) 

This  fact  was  repeatedly  insisted  upon  by  Sedgwick,  who, 
in  the  Syllabus  of  his  Cambridge  lectures,  published  very  early 
in  1837,  enumerated  the  principal  genera  and  species  of  Upper 
Cambrian  fossils,  many  of  which  were  by  him  declared  to  be 
the  same  with  those  of  the  Lower  Silurian  rocks  of  Murchison. 
Again,  in  enumerating  in  the  same  Syllabus  the  characteristic 
species  of  the  Bala  limestone,  it  is  added  by  Sedgwick:  "all  of 
which  are  common  to  the  Lower  Silurian  system."  This  was 
again  insisted  upon  by  him  in  1838  and  1841.  (Proc.  Geol. 
Soc.,  II.  679  ;  III.  548.)  It  was  not  until  1840  that  Bowman 
announced  the  same  conclusion,  which  was  reiterated  by 
Sharpe  in  1842.  (Ramsay,  Mem.  Geological  Survey,  III.  Part 
II.  p.  6.) 

In  1839,  Murchison  published  his  Silurian  System,  dedi- 
cated to  Sedgwick,  a  magnificent  work  in  two  volumes  quarto, 
with  a  separate  map,  numerous  sections,  and  figures  of  fossils. 
The  succession  of  the  Silurian  rocks,  as  there  given,  was  pre- 
cisely that  already  set  forth  by  the  author  in  1834,  and  again 
in  1835  ;  being,  in  descending  order,  Ludlow  and  Wenlock, 
constituting  the  Upper  Silurian,  and  Caradoc  and  Llandeilo 
(including  the  Lower  Llandeilo  beds  or  Stiper-stones),  the 
Lower  Silurian.  These  are  underlaid  by  the  Cambrian  rocks, 
into  which  the  Llandeilo  was  said  to  offer  a  transition  marked 
by  beds  of  passage.  Murchison,  in  fact,  declared  that  it  was 
impossible  to  draw  any  line  of  separation,  either  lithological, 
zoological,  or  stratigraphical,  between  the  base  of  the  Silurian 
beds  (Llandeilo)  and  the  upper  portion  of  the  Cambrian,  —  the 
whole  forming,  according  to  him,  in  Caermarthenshire,  one 
continuous  and  conformable  series  from  the  Cambrian  to  the 
Ludlow.  (Silurian  System,  pages  256,  258.)  By  Cambrian 


356  CAMBRIAN   AND   SILURIAN   IN   EUROPE.  [XV. 

in  this  connection  we  are  to  understand  only  the  Upper  Cam- 
brian or  Bala  group  of  Sedgwick,  as  appears  from  the  express 
statement  of  Murchison,  who  alludes  to  the  Cambrian  of  Sedg- 
wick as  including  all  the  older  slaty  rocks  of  Wales,  and  as 
divided  into  three  groups,  but  proceeds  to  say  that  in  his 
present  work  (the  Silurian  System)  he  shall  notice  only  the 
highest  of  these  three. 

Since  January,  1834,  when  Murchison  first  announced  the 
stratigraphical  relations  of  the  lower  division  of  what  he  after- 
wards called  the  Silurian  system,  the  aspect  of  the  case  had 
materially  changed.  This  division  was  no  longer  underlaid, 
both  to  the  east  in  Shropshire  and  to  the  west  in  Wales,  by  a 
great  unfossiliferous  series.  His  observations  in  the  •  vicinity 
of  the  Berwyn  hills  with  Sedgwick  in  1834,  and  the  subse- 
quently published  statements  of  the  latter,  had  shown  that 
this  supposed  older  series  was  not  without  fossils ;  but  on  the 
contrary,  in  North  Wales,  at  least,  held  a  fauna  identical  with 
that  characterizing  the  Lower  Silurian.  Hence  the  assertion  of 
Murchison  in  his  work  on  the  Silurian  System,  in  1839,  that  it 
was  not  possible  to  draw  any  line  of  demarcation  between 
them.  The  position  was  very  embarrassing  to  the  author  of 
the  Silurian  System,  and,  for  the  moment,  not  less  so  to  the 
discoverer  of  the  Upper  Cambrian  series.  Meanwhile,  the 
latter,  as  we  have  seen,  in  1842  re-examined  with  Salter  his 
Upper  Cambrian  sections  in  North  Wales,  and  satisfied  him- 
self of  the  correctness,  both  structurally  and  palseontologically, 
of  his  former  determinations.  Murchison,  in  his  anniversary 
address  as  President  of  the  Geological  Society  in  1842,  after 
recounting,  as  we  have  already  done,  the  history  of  the  naming 
by  Sedgwick,  in  1835,  of  the  Cambrian  series,  which  Murchi- 
son supposed  to  underlie  his  Silurian  system,  proceeded  as 
follows  :  "  Nothing  precise  was  then  known  of  the  organic 
contents  of  this  lower  or  Cambrian  system  except  that  some  of 
the  fossils  contained  in  its  upper  members  in  certain  prominent 
localities  were  published  Lower  Silurian  species.  Meanwhile, 
by  adopting  the  word  Cambrian,  my  friend  and  myself  were 
certain  that  whatever  might  prove  to  be  its  zoological  distinc- 


XV.]  CAMBRIAN  AND   SILURIAN  IN  EUROPE.  357 

tions,  this  great  system  of  slaty  rocks  being  evidently  inferior 
to  those  zones  which  had  been  worked  out  as  Silurian  types, 

no  ambiguity  could  hereafter  arise In  regard,  however, 

to  a  descending  zoological  order,  it  still  remained  to  be  proved 
whether  there  was  any  type  of  fossils  in  the  mass  of  the  Cam- 
brian rocks  different  from  those  of  the  Lower  Silurian  series. 
If  the  appeal  to  nature  should  be  answered  in  the  negative, 
then  it  was  clear  that  the  Lower  Silurian  type  must  be  consid- 
ered the  true  base  of  what  I  had  named  the  protozoic  rocks ; 
but  if  characteristic  new  forms  were  discovered,  then  would  the 
Cambrian  rocks,  whose  place  was  so  well  established  in  the 
descending  series,  have  also  their  own  fauna,  and  the  palaeozoic 
base  would  necessarily  be  removed  to  a  lower  horizon."  If  the 
first  of  these  alternatives  should  be  established,  or  in  other 
words,  if  the  fauna  of  the  Cambrian  rocks  was  found  to  be 
identical  with  that  of  the  Lower  Silurian,  then,  in  the  author's 
language,  "  the  term  Cambrian  must  cease  to  be  used  in  zoolog- 
ical classification,  it  being,  in  that  sense,  synonymous  with 
Lower  Silurian."  That  such  was  the  result  of  palaeontological 
inquiry,  Murchison  proceeded  to  show  by  repeating  the  an- 
nouncements already  made  by  Sedgwick  in  1837  and  1838, 
that  the  collections  made  by  the  latter  from  the  great  series  of 
fossiliferous  strata  in  the  Berwyns,  from  Bala,  from  Snowdon 
and  other  Cambrian  tracts,  were  identical  with  the  Lower 
Silurian  forms.  These  strata,  it  was  said,  contain  throughout 
"  the  same  forms  of  Orthis  which  typify  the  Lower  Silurian 
rocks."  It  was  further  declared  by  Murchison  in  this  address, 
that  researches  in  Germany,  Belgium,  and  Russia  led  to  the 
conclusion  that  the  "  fossiliferous  strata  characterized  by  Lower 
Silurian  Orthidte  are  the  oldest  beds  in  which  organic  life  has 
been  detected."  (Proc.  Geol.  Soc.,  III.  641,  et  seq.)  The 
Orthids  here  referred  to  are,  according  to  Salter,  Orthis  calli- 
gramma,  Dalm,  and  its  varieties.  (Mem.  Geol.  Survey,  III. 
Part  II.  335-337.) 

Meanwhile  Sedgwick's  views  and  position  began  to  be  mis- 
represented. In  1842,  Mr.  Sharpe.  after  calling  attention  to 
the  fact  that  the  fossils  of  the  Bala  limestone  were,  as  Sedgwick 


358  CAMBRIAN  AND   SILURIAN   IN  EUROPE.  [XV. 

had  long  before  shown,  identical  with  those  of  Murchison's 
Lower  Silurian,  declared  that  Sedgwick  had  placed  the  Upper 
Cambrian,  in  which  the  Bala  beds  were  included,  beneath  the 
Silurian,  and  that  this  determination  had  been  adopted  by  Mur- 
chison  on  Sedg wick's  authority.  (Proc.  Geol.  Soc.,  IY.  10.) 
This  statement  Murchison  suffered  to  pass  uncorrected  in  a 
complimentary  review  of  Sharpe's  paper  in  his  next  annual 
address  (1843).  Subsequently,  in  his  Siluria,  first  edition, 
page  25  (1854),  he  spoke  of  the  term  Cambrian  as  applied  (in 
1835)  by  Sedgwick  and  himself  "to  a  vast  succession  of  fossil- 
iferous  strata  containing  undescribed  fossils,  the  whole  of  which 
were  supposed  to  rise  up  from  beneath  well-known  Silurian 
rocks.  The  government  geologists  have  shown  that  this 
supposed  order  of  superposition  was  erroneous,"  etc.  The 
italics  are  the  author's.  Such  language,  coupled  with  Mr. 
Sharpe's  assertion  noticed  above,  helped  to  fix  upon  Sedgwick 
the  responsibility  of  Murchison's  error.  Although  the  histori- 
cal sketch,  which  precedes,  clearly  shows  the  real  position  of 
Sedgwick  in  the  matter,  we  may  quote  further  his  own  words  : 
"  I  have  often  spoken  of  the  great  Upper  Cambrian  group  of 
North  Wales  as  inferior  to  the  Silurian  system, ....  on  the 
sole  authority  of  the  Lower  Silurian  sections,  and  the  author's 
many  times  repeated  explanations  of  them  before  they  were  pub- 
lished. So  great  was  my  confidence  in  his  work,  that  I  received 
it  as  perfectly  established  truth  that  his  order  of  superposition 

was  unassailable I  asserted  again  and  again  that  the  Bala 

limestone  was  near  the  base  of  the  so-called  Upper  Cambrian 
group.  Murchison  asserted  and  illustrated  by  sections  the 
unvarying  fact  that  his  Llandeilo  flag  was  superior  to  the 
Upper  Cambrian  group.  There  was  no  difference  between  us, 
until  his  Llandeilo  sections  were  proved  to  be  wrong."  (Philos. 
Mag.  (4),  VIII.  506.)  That  there  must  be  a  great  mistake 
either  in  Sedgwick's  or  in  Murchison's  sections  was  evident, 
and  the  government  surveyors,  while  sustaining  the  correctness 
of  those  of  Sedgwick,  have  shown  the  sections  of  Murchison  to 
have  been  completely  erroneous. 

The  first  step  towards  an  exposure  of  the  errors  of  the  Silu- 


XV.]  CAMBRIAN  AND  SILURIAN   IN   EUROPE.  359 

rian  sections  is,  however,  due  to  Sedgwick  and  McCoy.  In 
order  better  to  understand  the  present  aspect  of  the  question, 
it  will  be  necessary  to  state  in  a  few  words  some  of  the  results 
which  have  been  arrived  at  by  the  government  surveyors  in 
their  studies  of  the  rocks  in  question,  as  set  forth  by  Kainsay 
in  the  Memoirs  of  the  Geological  Survey.  In  the  section  of 
the  Berwyns,  the  thin  bed  of  about  twenty  feet  of  Bala  lime- 
stone, which  (as  originally  described  by  Sedgwick)  they  have 
found  outcropping  on  both  sides  of  the  synclinal  chain,  is  shown 
to  be  intercalated  in  a  vast  thickness  of  Caradoc  rocks ;  being 
overlaid  by  about  3,300  and  underlaid  by  4,500  feet  of  strata 
belonging  to  this  formation.  Beneath  these  are  4,500  feet 
additional  of  beds  described  as  Llandeilo,  which  rest  uncon- 
formably  upon  the  Lingula  flags  just  to  the  west  of  Bala  ;  thus 
making  a  thickness  of  over  12,000  feet  of  strata  belonging  to 
the  Bala  group  of  Sedgwick.  A  small  portion  of  rocks  referred 
to  the  Wenlock  formation  occupies  the  synclinal  above  men- 
tioned. (Memoirs,  III.  Part  III.  214,  222.)  The  second  mem- 
ber, in  ascending  order,  of  the  Silurian  system,  to  which  the 
name  of  Caradoc  was  given  by  him  in  1839,  was  originally 
described  by  Murchison  under  the  names  of  the  Horderley  and 
May  Hill  sandstone.  The  higher  portions  of  the  Caradoc  were 
subsequently  distinguished  by  the  government  surveyors  as 
the  Lower  and  Upper  Llandovery  rocks ;  the  latter  (constitut- 
ing the  May  Hill  sandstone,  and  known  also  as  the  Pentamerus 
beds),  being  by  them  regarded  as  the  summit  of  the  Caradoc 
formation.  In  1852,  however,  Sedgwick  and  McCoy  showed 
from  its  fauna  that  the  May  Hill  sandstone  belongs  rather  to 
the  overlying  Wenlock  than  to  the  Caradoc  formation,  and 
marks  a  distinct  palseontological  horizon. 

This  discovery  led  the  geological  surveyors  to  re-examine  the 
Silurian  sections,  when  it  was  found  by  Aveline  that  there 
exists  in  Shropshire  a  complete  and  visible  want  of  conformity 
between  the  underlying  formations  and  the  May  Hill  sand- 
stone ;  the  latter  in  some  places  resting  upon  the  nearly  verti- 
cal Longmynd  rocks,  and  in  others  upon  the  Llandeilo  flags, 
the  Caradoc  proper  or  Bala  group,  and  the  Lower  Llandovery 


360  CAMBRIAN  AND   SILURIAN  IN   EUROPE.  [XV. 

beds.  Again,  in  South  "Wales,  near  Builth,  the  May  Hill 
sandstone  or  Upper  Llandovery  rests  upon  Lower  Llandeilo 
beds  ;  while  at  Noeth  Grug  the  overlying  formation  is  traced 
transgressively  from  the  Lower  Llandovery  across  the  Caradoc 
to  the  Llandeilo.  These  important  results  were  soon  con- 
firmed by  Earnsay  and  by  Sedgwick.  (Ibid.,  4,  236.)  The 
May  Hill  sandstone  often  includes,  near  its  base,  conglomerate 
beds  made  up  of  the  ruins  of  the  older  formation.  To  the 
northeast,  in  the  typical  Silurian  country,  it  is  of  great 
thickness  and  continuity,  but  gradually  thins  out  towards  the 
southwest. 

There  exists,  moreover,  another  region  where  not  less  curious 
discoveries  were  made.  About  forty  miles  to  the  eastward  of 
the  typical  region  in  South  Wales  appear  some  important 
areas  of  Silurian  rocks.  These  are  the  Woolhope  beds,  appear- 
ing through  the  Old  Eed  sandstone,  and  the  deposits  of 
Abberley,  the  Malverns,  and  May  Hill,  rising  along  its  eastern 
border,  and  covered  along  their  eastern  base  by  the  newer 
Mesozoic  sandstone.  The  rocks  of  these  localities  were  by 
Murchison  in  his  Silurian  System  described  as  offering  the 
complete  sequence.  When,  however,  it  was  found  that  his 
Caradoc  included  two  unconformable  series,  examination  showed 
that  there  was  no  representative  of  the  older  Caradoc  or  Bala 
group  in  these  eastern  regions,  but  that  the  so-called  Caradoc 
was  nothing  but  the  Upper  Llandovery  or  May  Hill  sandstone. 
The  immediately  underlying  strata,  which  Murchison  had 
regarded  as  Llandeilo,  or  rather  as  the  beds  of  passage  from 
Llandeilo  to  Cambrian,  and  had  compared  with  the  northwest 
parts  of  the  Caermarthenshire  sections  (Silurian  System,  416), 
have  since  been  found  to  be  much  more  ancient  deposits,  of 
Middle  Cambrian  age,  which  rest  upon  the  crystalline  hypozoic 
rocks  of  the  Malverns,  and  are  unconformably  overlaid  by  the 
May  Hill  sandstone.  We  shall  again  revert  to  this  region, 
which  has  been  carefully  studied  and  described  by  Professor 
John  Phillips.  (Mem.  Geol.  Sur.,  II.  Part  I.) 

What  then  was  the  value  and  the  significance  of  the  Silurian 
sections  of  Murchison,  when  examined  in  the  light  of  the 


XV.]  CAMBRIAN  AND   SILURIAN  IN   EUROPE.  361 

results  of  the  government  surveyors'?  The  Llandeilo  rocks, 
having  throughout  the  characteristic  Orthis  so  much  insisted 
upon  by  Murchison,  were  shown  to  be  the  base  of  a  great 
conformable  series,  and  to  the  eastward,  in  Shropshire,  to  rest 
on  the  upturned  edges  of  the  Longniynd  rocks ;  while  west- 
ward, near  Bala,  they  overlie  unconformably  the  Lingula  flags, 
and  in  the  island  of  Anglesea  repose  directly  upon  the  ancient 
crystalline  schists.  According  to  the  author  of  the  Silurian 
System,  there  existed  beneath  the  base  of  the  Llandeilo  forma- 
tion a  great  conformable  series  of  slaty  rocks  into  which  this 
formation  passed,  and  from  which  it  could  not  be  distinguished 
either  zoologically,  stratigraphically,  or  lithologically.  The 
sequence,  determined  from  what  were  considered  typical  sec- 
tions in  the  valley  of  the  Towey  in  Caermarthenshire,  as  given 
by  Murchison,  for  several  years  both  before  and  after  the  pub- 
lication of  his  work,  was  as  follows  :  1.  Cambrian ;  2.  Llan- 
deilo flags ;  3.  Caradoc  sandstone ;  4.  Wenlock  and  Ludlow 
beds ;  5.  Old  Red  sandstone ;  the  order  being  from  northwest 
to  southeast.  What,  then,  were  these  fossiliferous  Cambrian 
beds  underlying  the  Llandeilo  and  indistinguishable  from  it  ] 
Sedgwick,  with  the  aid  of  the  government  surveyors,  has  an- 
swered the  question  in  a  manner  which  is  well  illustrated  in 
his  ideal  section  across  the  valley  of  the  Towey.  The  whole 
of  the  Bala  or  Caradoc  group  rises  in  undulations  to  the  north- 
west, while  the  Llandeilo  flags  at  its  base  appear  on  an  anti- 
clinal in  the  valley,  and  are  succeeded  to  the  southeast  by  a 
portion  of  the  Bala.  The  great  mass  of  this  group  on  the 
southeast  side  of  the  anticlinal  is  however  concealed  by  the 
overlapping  May  Hill  sandstone,  —  the  base  of  the  unconform- 
able  upper  series  which  includes  the  Wenlock  and  Ludlow 
beds.  (Philos.  Mag.  (4),  VIII.  488.)  The  section  to  the 
southeast,  commencing  from  the  Llandeilo  flags  on  the  anti- 
clinal, was  made  by  Murchison  the  Silurian  system,  while  the 
great  mass  of  strata  on  the  northwest  side  of  the  Llandeilo 
(which  is  the  complete  representative  of  the  Caradoc  or  Bala 
beds,  partially  concealed  on  the  southwest  side)  was  supposed 
by  him  to  lie  beneath  the  Llandeilo,  and  was  called  Cambrian 
16 


362  CAMBRIAN  AND  SILURIAN  IN   EUROPE.  [XV. 

(the  Upper  Cambrian  of  Sedgwick).  These  rocks,  with  the 
Llandeilo  at  their  base,  were,  in  fact,  identical  with  the  Bala 
group  studied  by  the  latter  in  North  Wales,  and  are  now 
clearly  traced  through  all  the  intermediate  distance.  This  is 
admitted  by  Murchison,  who  says  :  "  The  first  rectification  of 
this  erroneous  view  was  made  in  1842  by  Professor  Ramsay, 
who  observed,  that  instead  of  being  succeeded  by  lower  rocks 
to  the  north  and  west,  the  Llandeilo  flags  folded  over  in  those 
directions,  and  passed  under  superior  strata,  charged  with 
fossils  which  Mr.  Salter  recognized  as  well-known  types  of  the 
Caradoc  or  Bala  beds."  (Siluria,  4th  ed.,  p.  57,  foot-note.) 

The  true  order  of  succession  in  South  Wales  was,  in  fact : 
1.  Llandeilo ;  2.  Cambrian  (=  Caradoc  or  Bala) ;  3.  Wenlock 
and  Ludlow ;  4.  Old  Red  sandstone ;  the  Caradoc  or  Bala  beds 
being  repeated  on  the  two  sides  of  the  anticlinal,  but  in  great 
part  concealed  on  the  southeast  side  by  the  overlapping  May 
Hill  or  Upper  Llandovery  rocks.  These  latter,  as  has  been 
shown,  form  the  true  base  of  the  upper  series  which,  in  the 
Silurian  sections,  was  represented  by  the  Wenlock  and  Ludlow. 
Murchison  had,  by  a  strange  oversight,  completely  inverted 
the  order  of  his  lower  series,  and  turned  the  inferior  members 
upside  down.  In  fact,  the  Llandeilo  flags,  instead  of  being,  as 
he  had  maintained,  superior  to  the  Cambrian  (Caradoc  or  Bala) 
beds,  were  really  inferior  to  them,  and  were  only  made  Silurian 
by  a  great  mistake.  The  Caradoc,  under  different  names,  was 
thus  made  to  do  duty  at  two  horizons  in  the  Silurian  system, 
both  below  and  above  the  Llandeilo  flags.  NOT  was  this  all, 
for  by  another  error,  as  we  have  seen,  the  Caradoc  in  the  latter 
position  was  made  to  include  the  Pentamerus  beds  of  the  un- 
conformably  overlying  series.  Thus  it  clearly  appears  that 
with  the  exception  of  the  relations  of  the  Wenlock  and  Lud- 
low beds  to  each  other  and  to  the  overlying  Old  Red  sand- 
stone, which  were  correctly  determined,  the  Sflurian  system  of 
Murchison  was  altogether  incorrect,  and  was  moreover  based 
upon  a  series  of  stratigraphical  mistakes  which  are  scarcely 
paralleled  in  the  history  of  geological  investigation. 

It  was  thus  that  the  Lower  Silurian  was  imposed  on  the 


XV.]  CAMBRIAN  AND  SILURIAN  IN   EUROPE.  363 

scientific  world ;  and  we  may  well  ask,  with  Sedgwick,  wheth- 
er geologists  "  would  have  accepted  the  Lower  Silurian  classifi- 
cation and  nomenclature  had  they  known  that  the  physical  or 
sectional  evidence  upon  which  it  was  based  had  been,  from  the 
first,  positively  misunderstood."  Feeling  that  his  own  sections 
were,  as  has  since  been  fully  established,  free  from  error,  Sedg- 
wick naturally  thought  his  name  of  Upper  Cambrian  should 
prevail  for  the  great  Bala  group.  Hence  the  long  and  imbit- 
tered  discussion  that  followed,  in  which  Murchison,  in  many 
respects,  occupied  a  position  of  vantage  as  against  the  Cambridge 
professor,  and  finally  saw  his  name  of  Lower  Silurian  supplant 
almost  entirely  that  of  Upper  Cambrian  given  by  Sedgwick, 
who  had  first  rightly  denned  and  interpreted  the  geological 
relations  of  the  group. 

In  a  paper  read  before  the  Geological  Society  in  June,  1843, 
(Proc.  Geol.  Soc.,  IV.  213-223)  when  the  perplexity  in  which 
the  relations  of  the  Upper  Cambrian  and  Lower  Silurian  rocks 
were  involved  had  not  been  cleared  up  by  the  discovery  of 
Murchison's  errors  in  stratigraphy,  Sedgwick  proposed  a  com- 
promise, according  to  which  the  strata  from  the  Bala  limestone 
to  the  base  of  the  Wenlock  were  to  take  the  name  of  Cambro- 
Silurian ;  while  that  of  Silurian  should  be  reserved  for  the 
Wenlock  and  Ludlow  beds,  and  for  those  below  the  Bala  the 
name  of  Cambrian  should  be  retained.  The  Festiniog  group 
(including  what  were  subsequently  named  the  Lingula  flags 
and  the  Tremadoc  slates)  would  thus  be  Upper  instead  of 
Middle  Cambrian,  the  original  Upper  Cambrian  being  hence- 
forth Cambro-Silurian  ;  it  being  understood  that,  wherever  the 
dividing  line  might  be  drawn,  all  the  groups  above  it  should 
be  called  Cambro-Silurian,  and  all  those  below  it  Cambrian. 
This  compromise  was  rejected  by  Murchison,  who  in  the  map 
accompanying  the  first  edition  of  his  Siluria,  in  1854,  extended 
the  Lower  Silurian  color  so  as  to  include  all  but  the  lowest 
division  of  the  Cambrian,  namely,  the  Bangor  group.  When, 
however,  the  relations  of  Upper  Cambrian  and  Silurian  were 
made  known  by  the  discoveries  of  Sedgwick  and  the  govern- 
ment surveyors,  this  compromise  was  seen  to  be  uncalled  for, 


364  CAMBRIAN  AND   SILURIAN  IN  EUROPE.  [XV. 

and  was  withdrawn  in  1854  by  Sedgwick,  who  reclaimed  the 
name  of  Upper  Cambrian  for  his  Bala  group. 

In  June,  1843,  Sedgwick  proposed  that  the  whole  of  the 
fossiliferous  rocks  below  the  horizon  of  the  Wenlock  should  be 
designated  Protozoic,  and  on  the  29th  of  November,  1843, 
presented  to  the  Geological  Society  an  elaborate  paper  on  the 
Older  Palaeozoic  (Protozoic)  Eocks  of  North  Wales,  with  a 
colored  geological  map.  This  paper,  which  embodied  the 
results  of  the  researches  of  Sedgwick  and  Salter,  was  not, 
however,  published  at  length,  but  an  abstract  of  it  was  pre- 
pared by  Mr.  Warburton,  then  president  of  the  society,  with  a 
reduced  copy  of  the  map.  (Proc.  Geol.  Soc.,  IV.  212  and 
251  -  268  j  also  Geol.  Jour.,  I.  5  -  22.)  In  this  map  of  Sedg- 
wick's  three  divisions  were  established,  namely,  the  hypozoic 
crystalline  schists  of  Caernarvonshire,  the  "  Protozoic  "  and  the 
"  Silurian."  On  the  legend  of  the  reduced  map,  as  published 
by  the  Geological  Society,  these  latter  names  were  altered  so 
as  to  read  "  Lower  Silurian  (Protozoic)"  and  "  Upper  Silurian." 
These  changes,  in  conformity  with  the  nomenclature  of  Mur- 
chison,  were,  it  is  unnecessary  to  say,  made  without  the 
knowledge  of  Sedgwick,  who  did  not  inspect  the  reduced  and 
altered  map  until  it  was  appealed  to  as  an  evidence  that  he  had 
abandoned  his  former  ground,  and  had  recognized  the  equiva- 
lency of  the  whole  of  his  Cambrian  with  the  Lower  Silurian  of 
Murchison.  The  reader  will  sympathize  with  the  indignation 
with  which  Sedgwick  declares  that  his  map  was  "most  un- 
warrantably tampered  with,"  and  will,  moreover,  learn  with 
surprise  that  an  inspection  of  the  proof-sheets  of  Warburton's 
abstract  of  Sedgwick's  paper  was  refused  him,  notwithstanding 
his  repeated  solicitations.  The  story  of  all  this,  and  finally  of 
the  refusal  to  print  in  the  pages  of  the  Geological  Journal  the 
reclamations  of  the  venerable  and  aggrieved  author,  make 
altogether  a  painful  chapter,  which  will  be  found  in  the 
Philos.  Magazine  for  1854  ((4)  VII.  pp.  301-317,  359-370, 
and  483  -  506),  and  more  fully  in  the  Synopsis  of  British 
Palaeozoic  Rocks,  which  forms  the  Introduction  to  McCoy's 
British  Paleozoic  Fossils. 


XV.]  CAMBRIAN  AND  SILURIAN   IN   EUROPE.  365 

In  connection  with  this  history  it  may  be  mentioned  that  in 
March,  1845,  Sedgwick  presented  to  the  Geological  Society  a 
paper  on  the  Comparative  Classification  of  the  Fossiliferous 
Rocks  of  North  Wales  and  those  of  Cumberland,  Westmore- 
land, and  Lancashire ;  which  appears  also  in  abstract  in  the 
same  volume  of  the  Geological  Journal  that  contains  the  ab- 
stract of  the  essay  and  the  map  just  referred  to.  (I.  442.) 
That  this  abstract  also  is  made  by  another  than  the  author  is 
evident  from  such  an  expression  as  "the  author's  opinion 
seems  to  be  grounded  on  the  following  facts,"  etc.,  (p.  448)  and 
from  the  manner  in  which  the  terms  Lower  and  Upper  Silurian 
are  applied  to  certain  fossiliferous  rocks  in  Cumberland.  Yet 
the  words  of  this  abstract  are  quoted  with  emphasis  in  Siluria 
(1st.  ed.,  147),  as  if  they  were  Sedgwick's  own  language  recog- 
nizing Murchison's  Silurian  nomenclature.* 

II.    MIDDLE  AND  LOWER  CAMBRIAN. 

Investigations  in  continental  Europe  were,  meanwhile,  pre- 
paring the  way  for  a  new  chapter  in  the  history  of  the  lower 
palaeozoic  rocks.  A  series  of  sedimentary  beds  in  Sweden  and 
Norway  had  long  been  known  to  abound  in  singular  petrifica- 
tions,  some  of  which  had  been  examined  by  Linnaeus,  who 
gave  to  them  the  name  of  Entomolithi.  They  were  also  studied 
and  described  by  Wahlenberg  and  by  Brongniart,  the  latter  of 
whom,  from  two  varieties  of  the  Entomolithus  pamdoxus,  Linn., 
established  in  1822  two  genera,  Paradoxides  and  Agnostus. 
In  1826  appeared  a  memoir  by  Dalman  on  the  Palaeadae,  or 
so-called  Trilobites;  which  was  followed,  in  1828,  by  his 
classic  work  on  the  same  subject.  (liber  die  Palaeaden  oder 
so-genannten  Trilobiten,  4to,  with  six  plates,  Leipsic.)  In 
these  works  were  described  and  figured,  among  many  others, 
two  genera,  —  Olenus,  which  included  Paradoxides,  Brongn., 

*  [A  letter  to  the  author,  written  him  by  the  late  Professor  Sedgwick  after 
reading  the  above,  confirms  the  opinion  here  expressed.  The  abstract  in 
question  was  furnished  by  Murchison  himself  to  the  Geological  Society, 
the  secretary  of  which  declined  to  receive  the  abstract  offered  by  Sedgwick  of 
his  own  paper.] 


366  CAMBRIAN  AND   SILURIAN   IN  EUROPE.  [XV. 

and  Battus,  including  Agnostus  of  the  same  author.  Mean- 
while, Hisinger  was  carefully  studying  the  strata  in  which 
these  trilohites  were  found  in  Gothland,  and  in  the  same  year 
(1828)  published  in  his  Anteckningar,  or  Notes  on  the  Physical 
and  Geognostical  Structure  of  Norway  and  Sweden,  a  colored 
geological  map  and  section  of  these  rocks  as  they  occur  in  the 
county  of  Skaraborg  ;  where  three  small  circumscribed  areas  of 
nearly  horizontal  fossiliferous  strata  are  shown  to  rest  upon  a 
floor  of  old  crystalline  rocks,  in  some  parts  granitic  and  in 
others  gneissic  in  character.  The  section  and  map,  as  given 
by  Hisinger,  show  the  succession  in  the  principal  area  to  be  as 
follows,  in  ascending  order  :  1.  Granite  or  gneiss  ;  2.  Sandstone  ; 
3.  Alum-slates  ;  5.  Orthoceratite-limestones  ;  4.  Clay-slates.  By 
a  curious  oversight  the  colors  on  the  legend  are  wrongly  ar- 
ranged and  wrongly  numbered,  as  above ;  for  in  the  map  and 
section  it  is  made  clear  that  the  succession  is  that  just  given, 
and  that  the  clay-slates  (4),  instead  of  being  below,  are  above 
the  orthoceratite-limestones  (5). 

In  1837,  Hisinger  published  his  great  work  on  the  organic 
remains  of  Sweden,  entitled  Lethoea  Suecica  (4to,  with  forty- 
two  plates).  In  this  he  gives  a  tabular  view,  in  descending 
order,  of  the  rock-formations,  and  of  the  various  genera  and 
species  described.  The  rocks  of  the  areas  just  noticed  appear 
in  his  fourth  or  lowest  division,  under  the  head  of  Forma- 
tiones  transitiQnis,  and  are  divided  as  follows  :  — 

a.  Strata  calcarea  recentiora  Gottlandise. 

b.  Strata  schisti  argillacei. 

c.  Strata  schisti  aluminaris. 

d.  Strata  calcarea  antiquiora. 

e.  Strata  saxi  arenacei. 

The  succession  thus  given  was,  however,  erroneous,  and  proba- 
bly, like  the  mistake  in  the  legend  of  the  same  author's  map 
just  mentioned,  the  result  of  inadvertence,  the  true  position 
of  the  alum-slates  (c)  being  between  the  older  limestone  (d) 
and  the  basal  sandstone  (e).  This  is  shown  both  by  Hisinger's 
map  of  1828,  and  by  the  testimony  of  subsequent  observers. 
In  Murchison's  work  on  the  Geology  of  Russia  in  Europe, 


XV.]  CAMBRIAN  AND   SILURIAN  IN  EUROPE.  367 

published  in  1845,  there  is  given  (page  15  et  seq.)  an  ac- 
count of  his  visit  to  this  region  in  company  with  Professor 
Loven,  of  Christiania ;  which,  with  figures  of  the  sections,  is 
reproduced  in  the  different  editions  of  Siluria.  The  hill  of  Kin- 
nekulle,  on  Lake  Wener,  is  one  of  the  three  areas  of  transition 
rocks  delineated  on  the  map  of  Hisinger  above  referred  to. 
Resting  upon  a  flat  region  of  nearly  vertical  gneissic  strata,  we 
have,  according  to  Murchison  :  1.  A  fucoidal  sandstone;  2. 
Alum-slates  ;  3.  Red  orthoceratite  limestone ;  4.  Black  grapto- 
litic  slates;  the  whole  series  being  little  over  1,000  feet  in 
thickness,  and  capped  by  erupted  greenstone.  Above  these 
higher  slates  there  are  found,  in  some  parts  of  Gothland,  other 
limestones  with  orthoceratites,  trilobites,  and  corals,  the  newer 
limestone  strata  (a)  of  Hisinger ;  the  whole  overlaid  by  thin 
sandstone  beds.  These  higher  limestones  and  sandstones  con- 
tain the  fauna  of  the  Wenlock  and  Ludlow  of  England ;  while 
the  lower  limestones  and  graptolitic  slates  afford  Calymene  Bl'Ur 
menbachii,  Orthis  calligramma,  and  many  other  species  com- 
mon to  the  Bala  group  of  North  Wales.  The  alum-slates 
below  these,  however,  contained,  according  to  Hisinger,  none  of 
the  species  then  known  in  British  rocks,  but  in  their  stead  five 
species  of  Olenus  and  two  of  Battus  (Agnostus). 

In  1854,  Angelin  published  his  Palceontologica  Scandinavica, 
Part  I.,  Crustacea  ' formationis  transitionis  [4to,  forty-one 
plates],  in  which  he  divided  the  series  of  transition  rocks 
above  described  by  Hisinger  into  eight  parts,  designated  by 
Roman  numerals,  counting  from  the  base.  Of  these  I.  was 
named  Regio  Fucoidarum,  no  organic  remains  other  than 
fucoids  being  known  therein  ;  while  the  remaining  seven  were 
named  from  their  characteristic  genera  of  trilobites,  which 
were  as  follows,  in  ascending  order,  certain  letters  being  also 
used  to  designate  the  parts :  II.  (A)  Olenus ;  III.  (B)  Cono- 
coryphe;  IV.  (BC)  Ceratopyge ;  V.  (C)  Asaphus ;  VI.  (D) 
Trinucleus  ;  VII.  (DE)  Harpes ;  VIII.  (E)  Cryptonymus.  In 
the  Regio  Olenorum  (II.)  was  found  also  the  allied  genus  Para- 
doxides.  With  regard  to  the  characteristic  genus  of  Regio  III., 
the  name  of  Conocoryphe  was  proposed  for  it  by  Corda  in  1847, 


368  CAMBRIAN  AND  SILURIAN  IN  EUROPE.  [XV. 

as  synonymous  with  Zenker's  name  of   Conocephalus   (Cono- 
cephalites),  already  appropriated  to  a  genus  of  insects. 

Meanwhile,  the  similar  crustaceans  which  abound  in  the 
transition  rocks  of  Bohemia  had  been  studied  and  described  by 
Hawle,  Corda,  and  Beyrich,  when  Barrande  began  his  admi- 
rable investigations  of  this  ancient  fauna  and  of  its  stratigraph- 
ical  relations.  He  soon  found  that  beneath  the  horizon  charac- 
terized by  fossils  of  the  Bala  group  (Llandeilo  and  Caradoc) 
there  existed  in  Bohemia  a  series  of  strata  distinguished  by  a 
remarkable  fauna,  entirely  distinct  from  anything  known  in 
Great  Britain,  but  closely  allied  to  that  of  the  alum-slates  of 
Scandinavia,  corresponding  to  Regiones  II.  and  III.  of 
Angelin.  To  this  he  gave  the  name  of  the  first  or  primordial 
fauna,  and  to  the  rocks  yielding  it  that  of  the  Primordial  Zone. 
Resting  upon  the  old  gneisses  of  Bohemia  appears  a  series  of 
crystalline  schists  designated  by  Barrande  as  Etage  A,  overlaid 
by  a  series  of  sandstones  and  conglomerates,  Etage  B,  upon 
which  repose  the  fossiliferous  argillites  of  the  primordial  zone, 
or  Etage  C.  The  rocks  of  the  Etages  A  and  B  were  by  Bar- 
rande regarded  as  azoic,  but,  in  1861,  Fritsch  of  Prague,  after  a 
careful  search,  discovered  in  certain  thin-bedded  sandstones  of 
B  the  traces  of  filled-up  vertical  double  tubes  ;  which,  accord- 
ing to  Salter  (Mem.  Geol.  Sur.,  III.  243),  are  probably  the 
marks  of  annelides,  and  are  identical  with  those  found  in  the 
rocks  of  the  Bangor  or  Longmynd  group  in  Great  Britain, 
which  will  be  shown  to  belong  to  the  primordial  zone.  It  is, 
therefore,  probable  that  the  Etage  B,  which  apparently  cor- 
responds to  the.  Regio  Fucoidarum  or  basal  sandstone  of 
Scandinavia,  should  itself  be  included  in  the  primordial  zone. 
It  may  here  be  noticed  that  it  is  in  the  crystalline  schists  of  A 
that  Giimbel  has  found  Eozoon  Bavaricum.  To  the  Etage  C  in 
Bohemia,  Barrande  assigns  a  thickness  of  about  1,200  feet,  and 
to  this  his  first  fauna  is  confined,  while  in  the  succeeding 
divisions  he  distinguished  a  second  and  a  third.  The  second 
fauna,  which  characterizes  Etage  D,  corresponds  to  that  of  the 
Bala  group ;  while  the  third  fauna,  belonging  to  the  Etages  E, 
F,  G,  and  H,  is  that  of  the  May  Hill,  Wenlock,  and  Ludlow 
formations  of  Great  Britain. 


XV.]  CAMBRIAN  AND   SILURIAN   IN   EUROPE.  369 

This  classification  of  the  ancient  Bohemian  faunas  was  first 
set  forth  by  Barrande  in  1846,  in  his  Notice  Preliminaire, 
in  which  he  declared  that  the  first  fauna  was  below  the  base  of 
the  Llandeilo  of  Murchison,  unknown  in  Great  Britain,  and, 
moreover,  "  new  and  independent  in  relation  to  the  two  Silu- 
rian faunas  (his  second  and  third)  already  established  in 
England."  This  opinion  he  reiterated  in  1859.  These  three 
divisions  form  in  Bohemia  an  apparently  continuous  series,  and 
being  connected  with  each  other  by  some  common  species, 
Barrande  was  led  to  look  upon  the  whole  as  forming  a  single 
stratigraphical  system ;  and  finally  to  assert  that  these  three 
independent  faunas  "  form  by  their  union  an  indivisible  triad, 
which  is  the  Silurian  system."  (Bull.  Soc.  Geol.  de  Fr.  (2), 
XVI.  529-545.)  Already,  in  1852,  in  his  magnificent  work 
on  the  Silurian  System  of  Bohemia,  Barrande  had  given  to  the 
strata  characterized  by  his  first  fauna  the  name  of  Primordial 
Silurian.  It  is  difficult  to  assign  any  just  reason  for  thus  an- 
nexing to  the  Silurian  —  already  augmented  by  the  whole 
Upper  Cambrian  or  Bala  group  of  Sedgwick  (Llandeilo  and 
Caradoc)  —  a  great  series  of  fossiliferous  rocks  lying  below  the 
base  of  the  Llandeilo,  and  unsuspected  by  the  author  of  the 
Silurian  System,  who  persistently  claimed  the  Llandeilo  beds, 
with  their  characteristic  second  fauna,  as  marking  the  dawn  of 
organic  life. 

Up  to  this  time  the  primordial  paleozoic  fauna  of  Bohemia 
and  of  Scandinavia  was,  as  we  have  said,  unknown  in  Great 
Britain.  The  few  organic  remains  mentioned  by  Sedgwick  in 
1835  as  occurring  in  the  region  occupied  by  his  Lower  and 
Middle  Cambrian,  on  Snowdon,  were  found  to  belong  to  Bala 
beds,  which  there  rest  upon  the  older  rocks :  nor  was  it  until 
1845  that  Mr.  Davis  found  in  the  Middle  Cambrian  remains 
of  Lingula.  In  1846,  Sedgwick,  in  company  with  Mr.  Davis, 
re-examined  these  rocks,  and  in  December  of  the  same  year 
described  the  Lingula  beds  as  overlaid  by  the  Tremadoc  slates 
and  occupying  a  well-defined  horizon  in  Caernarvon  and  Me- 
rionethshire, beneath  the  great  mass  of  the  Upper  Cambrian 
rocks.  (GeoL  Jour.,  IL  75;  III.  139.)  Sedgwick,  at  the  same 
16*  x 


370  CAMBRIAN  AND   SILUKIAN  IN   EUROPE.  [XV. 

time,  noticed  about  this  horizon  certain  graptolites  and  an 
Asaphus,  which  were  supposed  to  belong  to  the  Tremadcc 
slates,  but  have  since  been  declared  by  Salter  to  pertain  to  the 
Arenig  or  Lower  Llandeilo  beds,  the  base  of  the  Upper  Cam- 
brian. (Mem.  Geol.  Sur.,  III.  257,  and  Decade  II.) 

This  discovery  of  the  Lingula  nags,  as  they  were  then  named, 
and  the  fixing  by  Sedgwick  of  their  geological  horizon,  was  at 
once  followed  by  a  careful  examination  of  them  by  the  govern- 
ment surveyors,  and  in  1847,  Selwyn  detected  in  the  Lingula 
flags,  near  Dolgelly,  in  Merionethshire,  the  remains  of  two 
crustacean  forms,  the  one  a  phyllopod,  which  has  received  the 
name  of  Hymenocaris  vermicauda,  Salter,  and  the  other  a 
trilobite  which  was  described  by  Salter  in  1849  as  Olenus 
micrurm.  (Geol.  Survey,  Decade  II.)  A  species  of  Para- 
doxides,  apparently  identical  with  P.  Forchhammeri  of  Swe- 
den, was  also  about  this  time  recognized  among  specimens 
supposed  to  be  from  the  same  horizon.  It  has  since  been  de- 
scribed as  P.  Jfficksii,  and  found  to  belong  to  the  basal  beds  of 
the  Lingula  flags,  —  the  Menevian  group. 

Upon  the  flanks  of  the  Malvern  Hills  there  is  found  resting 
upon  the  ancient  crystalline  rocks  of  the  region,  and  overlaid 
by  the  Pentamerus  beds  of  the  May  Hill  sandstone  (originally 
called  Caradoc  by  Murchison)  a  series  of  fossiliferous  beds. 
These  consist  in  their  lowest  part  of  about  600  feet  of  greenish 
sandstone,  which  have  since  yielded  an  Obolella  and  Serpu- 
lites,  and  are  overlaid  by  500  feet  of  black  schists.  In  these, 
in  1842,  Professor  John  Phillips  found  the  remains  of  trilo- 
bites,  which  he  subsequently  described,  in  1848,  as  three 
species  of  Olenus.  (Mem.  Geol.  Survey,  II.  Part  I.  55.) 
These  black  shales,  which  had  not  at  that  time  furnished  any 
organic  remains,  were  by  Murchison  in  his  Silurian  System 
(p.  416)  in  1839  compared  to  the  supposed  passage-beds  in 
Caermarthenshire  between  the  Llandeilo  and  the  Cambrian 
(Bala)  rocks  ;  which,  as  we  have  seen,  were  newer  and  not 
older  strata  than  the  Llandeilo  flags.  From  their  lithological 
characters,  and  their  relations  to  the  Pentamerus  beds,  these 
lower  fossiliferous  strata  of  Malvern  were  subsequently  referred 


XV.]  CAMBRIAN  AND   SILURIAN  IN   EUROPE.  371 

by  the  government  geologists  to  the  horizon  of  the  Caradoc 
proper  or  Bala  group ;  nor  was  it  until  1 85 1  that  their  true 
geological  age  and  significance  were  made  known.  In  that 
year,  Barrande,  fresh  from  the  study  of  the  older  rocks  of  the 
continent,  came  to  England  for  the  purpose  of  comparing 
the  British  fossils  with  those  of  the  primordial  zone,  which 
he  had  established  in  Bohemia  and  Scandinavia,  and  which 
he  at  once  recognized  in  the  Lingula  flags  of  Sedgwick  and 
in  the  black  schists  at  Malvern ;  both  of  which  were  char- 
acterized by  the  presence  of  the  genus  Olenus,  and  were 
referred  to  the  horizon  of  his  Etage  C.  This  important  con- 
clusion was  announced  by  Salter  to  the  British  Association  at 
Belfast  in  1852.  (Rep.  Brit.  Assoc.,  abstracts,  p.  56,  and 
Bull.  Soc.  GeoL  de  Fr.  (2),  XVI.  537.)  [The  black  schists  of 
Malvern,  and  the  underlying  greenish  beds  known  as  the 
Hollybush  sandstones,  are  by  Hicks  regarded  as  the  equivalents 
respectively  of  the  Dolgelly  and  Festiniog  divisions  of  the  Lin- 
gula-flags.  (Proc.  Geologists'  Association,  Vol.  III.  Xo.  3.)] 
The  palaeontological  studies  of  Salter,  while  they  confirmed 
the  primordial  character  of  the  whole  of  the  great  mass  of  strata 
which  make  up  the  Middle  Cambrian  or  Festiniog  group  of 
Sedgwick  (consisting  of  the  Lingula  flags  and  the  Tremadoc 
slates),  led  him  to  propose  several  subdivisions.  Thus  he 
distinguished  on  palseontological  grounds  between  the  upper 
and  lower  Tremadoc  slates,  and  for  like  reasons  divided  the 
Lingula  flags  into  a  lower  and  an  upper  portion.  For  the 
discussion  of  these  distinctions  the  reader  is  referred  to  the 
memoirs  of  the  Geol.  Survey  (III.  240-257).  Subsequent 
researches  led  to  the  division  of  the  original  Lingula  flags  into 
four  parts,  an  upper,  middle,  and  lower,  to  which  the  names 
of  Dolgelly,  Festiniog,  and  Maentwrog  were  given  by  Mr. 
Belt  in  1867,  and  a  fourth,  consisting  of  the  basal  beds,  which 
had  been  already  separated  in  1865  by  Salter  and  Hicks,  with 
the  designation  of  Menevian,  derived  from  the  ancient  Roman 
name  of  St.  David's  in  Pembrokeshire.*  It  was  here  that,  in 

[*  The  researches  of  Mr.  Belt  on  the  Lingula  Flags  appeared  in  1867. 
(Geological   Magazine,  Vol.  IV.  483  and  536,  and  Vol.  V.  5.)    He  included 


372  CAMBRIAN  AND   SILURIAN   IN  EUROPE.  [XV. 

1862,  Salter  found  Paradoxides  with  Agnostus  and  Lingula  in 
fine  black  shales  at  the  base  of  the  Lingula  flags,  resting  con- 
formably on  the  green  and  purple  grits  of  the  Lower  Cambrian 
or  Harlech  beds.  The  locality  was  afterwards  carefully  studied 
by  Hicks,  and  it  was  soon  made  apparent  that  the  genus  Para- 
doxides, both  here  and  in  North  Wales,  was  confined  to  a 
horizon  below  the  great  mass  of  the  Lingula  flags ;  which,  on 
the  contrary,  are  characterized  by  numerous  species  of  Ole- 
nus.  These  lower  or  Menevian  beds  are  hence  regarded  by 
Salter  as  equivalent  to  the  lowest  portion  of  the  Etage  C  of 
Barrande. 

Beneath  these  Menevian  beds  there  lies,  in  apparent  con- 
formity, the  great  Lower  Cambrian  series,  frequently  called  the 
bottom  or  basement  rocks  by  the  government  surveyors ;  rep- 
resented in  North  Wales  by  the  Harlech  grits,  and  in  South 
Wales,  near  St.  David's,  by  a  similar  series  of  green  and  purple 
sandstones,  considered  by  Murchison,  and  by  others,  as  the 
equivalent  of  the  Harlech  rocks.  They  were  still  supposed  to 
be  unfossiliferous  until  in  June,  1867,  Salter  and  Hicks  an- 
nounced the  discovery  in  the  red  beds  of  this  lower  series,  at 
St.  David's,  of  a  Lingulella,  very  like  L.  ferruginea  of  the 
Menevian.  (Geol.  Jour.,  XXIII.  339  ;  Siluria,  4th  ed.,  550.) 
This  led  to  a  further  examination  of  these  Lower  Cambrian 
beds,  which  has  resulted  in  the  discovery  in  them  of  a  fauna 
distinctly  primordial  in  type,  and  linked  by  the  presence  of 
several  identical  fossils  to  the  Menevian  ;  but  in  many  respects 
distinct,  and  marking  a  lower  fossiliferous  horizon  than  any- 
thing known  in  Bohemia  or  in  Scandinavia. 

The  first  announcement  of  these  important  results  was  made 

tinder  the  name  of  Upper  Cambrian  the  Tremadoc  rocks  with  the  Lingula 
flags  proper,  which  he  divided  in  descending  order  into  three  parts,  Dolgelly, 
Festiniog,  and  Maentwrog ;  while  he  suggested  the  union  of  the  basal  beds, 
(previously  separated  under  the  name  of  Menevian,)  with  the  underlying 
Harlech  and  Bangor  rocks  as  Lower  Cambrian.  These  divisions  of  Belt  are 
now  recognized  by  Hicks.  It  will  be  recollected  that  the  whole  of  the 
Lingula  flags  were  originally  included  in  his  Festiniog  group  by  Sedgwick. 
All  of  these  rocks-  are  inverted  in  the  vicinity  of  Dolgelly,  the  apparent 
succession  iu  descending  order  being  Festiniog,  Dolgelly,  Tremadoc,  and 
Arenig.] 


XV.]  CAMBRIAN   AND   SILURIAN  IN   EUROPE.  373 

to  the  British  Association  at  Norwich  in  1868.  Further  details 
were,  however,  laid  before  the  Geological  Society  in  May, 
1871,  by  Messrs.  Harkness  and  Hicks,  whose  paper  on  The 
Ancient  Rocks  of  St.  David's  Promontory  appears  in  the 
Geological  JournaPfor  November,  1871.  (XXVIII.  384.) 
The  Cambrian  sediments  here  rest  upon  an  older  series  of 
crystalline  stratified  rocks,  described  by  the  geological  sur- 
veyors as  syenite  and  greenstone,  and  having  a  northwest 
strike.  Lying  unconformably  upon  these,  and  with  a  north- 
east strike,  we  have  the  following  series,  in  ascending  order : 
1.  Quartzose  conglomerate,  60  feet;  2.  Greenish  flaggy  sand- 
stones, 460  feet ;  3.  Red  flags  or  slaty  beds,  50  feet,  containing 
Lingulella  ferruginea,  besides  a  larger  species,  Discina,  and 
Leperditia  Cambreiisis ;  4.  Purple  and  greenish  sandstones, 
1,000  feet;  5.  Yellowish-gray  sandstones,  flags,  and  shales, 
150  feet,  with  Plutonia,  Conocoryphe,  Microdiscus,  Agnostus, 
T/ieca,  and  Protospongia  ;  6.  Gray,  purple,  and  red  flaggy  sand- 
stones, with  most  of  the  above  genera,  1,500  feet ;  7.  Gray 
flaggy  beds,  150  feet,  with  Paradoxides ;  8.  True  Menevian 
beds,  richly  fossiliferous,  500  feet.  The  latter  are  the  probablo 
equivalent  of  the  base  of  Barrande's  Etage  C,  and  at  St.  David's 
are  conformably  overlaid  by  the  Lingula  flags ;  beneath  which 
we  have,  including  the  Menevian,  a  conformable  series  of 
3,370  feet  of  uncrystalline  sediments,  fossiliferous  nearly  to  the 
base,  and  holding  a  well-marked  fauna  distinct  from  anything 
hitherto  known  in  Great  Britain  or  elsewhere. 

The  Menevian  beds  are  connected  with  the  underlying  strata 
by  the  presence  of  Lingulella  ferruginea,  Discina  pileolus,  and 
Obolella  sagittatis,  which  extend  v  through  the  whole  series ; 
and  also  by  the  genus  Paradoxides,  four  species  of  which  occur 
in  these  lower  strata  ;  from  which  the  genus  Olenus,  which 
characterises  the  Lingula  flags,  seems  to  be  absent.  To  a  large 
tuberculated  trilobite  of  a  new  genus  found  in  these  lowest 
rocks  the  name  of  Plulonia  Sedgwickii  has  been  given.  Hicks 
has  proposed  to  unite  the  Menevian  with  the  Harlech  beds, 
and  to  make  the  summit  of  the  former  the  dividing  line  be- 
tween the  Lower  and  Middle  Cambrian,  a  suggestion  which 


374  CAMBRIAN  AND   SILURIAN   IN   EUROPE.  [XV. 

has  been  adopted  by  Lyell.     (Proc.  Brit.  Assoc.  for  1868,  p. 
68,  and  Lyell,  Student's  Manual  of  Geology,  466  -  469.) 

Both  Phillips  and  Lyell  give  the  name  of  Upper  Cambrian 
to  the  Lingula  flags  and  the  Tremadoc  slates,  which  together 
constitute  the  Middle  Cambrian  of  Sedgwick,  and  concede  the 
title  of  Lower  Silurian  to  the  Bala  group  or  Upper  Cambrian 
of  Sedgwick.  The  same  view  is  adopted  by  Linnarsson  in 
Sweden,  who  places  the  line  between  Cambrian  and  Silurian 
at  the  base  of  the  Llandeilo  or  the  second  fauna.  It  was  by 
following  these  authorities  that  I,  inadvertently,  in  my  address 
to  the  American  Association  for  the  Advancement  of  Science 
in  August,  1871,  gave  this  horizon  as  the  original  division 
between  Cambrian  and  Silurian.*  The  reader  of  the  first  part 
of  this  paper  will  see  with  how  much  justice  Sedgwick  claims 
for  the  Cambrian  the  whole  of  the  fossiliferous  rocks  of  Wales 
beneath  the  base  of  the  May  Hill  sandstone,  including  both 
the  first  and  the  second  fauna.  I  cannot  but  agree  with  the 
late  Henry  Darwin  Rogers,  who,  in  1856,  reserved  the  designa- 
tion of  "  the  true  European  Silurian  "  for  the  rocks  above  this 
horizon.  (Keith  Johnson's  Physical  Atlas,  2d  ed.) 

The  Lingula  flags  and  Tremadoc  slates  have  been  made  the 
subject  of  careful  stratigraphical  and  palseontological  studies  by 
the  Geological  Survey,  the  results  of  which  are  set  forth  by 
Eamsay  and  Salter  in  the  third  volume  of  the  Memoirs  of  the 
Geological  Survey,  published  in  1866,  and  also,  more  concisely, 
in  the  Anniversary  Address  by  the  former  to  the  Geological 
Society  in  1863.  (Geol.  Jour.  (19),  XVIII.)  The  Lingula 
flags  (with  the  underlying  Menevian,  which  resembles  them 
lithologically)  rest  in  apparent  conformity  upon  the  purple 
Harlech  rocks  both  in  Pembrokeshire  and  in  Merionethshire, 
where  the  latter  appear  on  the  great  Merioneth  anticlinal,  long 
since  pointed  out  by  Sedgwick.  The  Lingula  flags,  (including 
the  Menevian)  have  in  this  region,  according  to  Ramsay,  a 
thickness  of  about  6,000  feet.  Above  these,  near  Tremadoc 
and  Festiniog,  lie  the  Tremadoc  slates,  which  are  here  overlaid, 
in  apparent  conformity,  by  the  Lower  Llandeilo  beds.  At  a 

*  Since  corrected  in  the  reprint  of  that  address  in  the  present  volume. 


XV.]  CAMBRIAN  AND  SILURIAN  IN   EUROPE.  375 

distance  of  eleven  miles  to  the  northwest,  however,  the  Tre- 
inadoc  slates  disappear,  and  the  Lingula  flags  are  represented 
by  only  2,000  feet  of  strata ;  while  in  parts  of  Caernarvonshire, 
and  in  Anglesea,  the  whole  of  the  Lingula  flags  and,  moreover, 
the  Lower  Cambrian  rocks  are  wanting,  and  the  Llandeilo  beds 
rest  directly  upon  the  ancient  crystalline  schists.  In  Scotland 
and  in  Ireland,  moreover,  the  Lingula  flags  are  wholly  absent, 
and  the  Llandeilo  rocks  there  repose  unconformably  upon 
grits  regarded  as  of  Lower  Cambrian  age.  Thus,  without 
counting  the  Treinadoc  slates,  which  are  a  local  formation, 
unknown  out  of  Merionethshire,*  we  have  (including  the 
Bangor  group  and  Lingula  flags),  beneath  the  Llandeilo,  over 
9,000  feet  of  fossiliferous  strata,  which  disappear  entirely  in 
the  distance  of  a  few  miles.  From  a  careful  survey  of  all  the 
facts,  the  conclusion  of  Bamsay  is  irresistible,  that  there  exists 
between  the  Lingula  flags  and  the  Llandeilo  not  merely  one, 
but  two  great  stratigraphical  breaks  in  the  succession  ;  the  one 
between  the  Lingula  flags  and  the  Lower  Tremadoc  slates,  and 
the  other  between  the  Upper  Tremadoc  slates  and  the  Lower 
Llandeilo,  at  the  base  of  which  were  included  the  Arenig  rocks. 
This  conclusion  is  confirmed  by  the  fact  that  there  exists  at 
each  of  these  horizons  a  nearly  complete  palaeontological  break. 

*  [This  statement  requires  correction,  since  already,  in  1866,  Messrs.  Salter 
and  Hicks  had  mentioned  the  occurrence  of  rocks  supposed  to  be  of  that  age 
near  St.  David's  in  South  Wales,  and  very  recently,  in  the  Quarterly  Geologi- 
cal Journal  for  February,  1873,  the  latter  has  given  a  description  of  the 
localities  of  Tremadoc  rocks  in  this  region,  with  figures  of  the  organic  remains,  a 
map,  and  sections.  The  beds  have  here  a  thickness  of  about  1,000  feet,  and  rest 
directly  upon  the  Lingula  flags.  The  apparent  want  of  conformity  between  the 
two  divisions  noticed  by  Ramsay  in  North  Wales  is  here  not  manifest.  They 
are  followed  in  seeming  unconformity  by  the  Arenig  rocks,  which  are  by  Mr. 
Homfray  considered  equivalent  to  the  Upper  Tremadoc  of  North  Wales,  and 
contain  in  abundance  the  graptolites  of  the  Levis  formation  of  Canada.  The 
beds  between  these  and  the  Lingula  flags  hold  a  rich  fauna  closely  allied  to 
the  Lower  Tremadoc,  including  an  Orthoceras,  a  new  species  of  Paleasterina, 
and  a  Dendrncrinus,  various  brachiopods  and  lamellibranchs,  trilobites  of 
the  genus  Niobe  and  of  a  new  genus,  Neseuretus,  closely  allied  to  Dikeloceph- 
rtZi/.s,  to  which  Hicks  refers  the  supposed  species  of  D.  described  by  Salter 
from  the  Upper  Lingula  and  Lower  Tremadoc  rocks  of  North  Wales ;  the  only 
true  Dike.locephalius  in  Wales,  according  to  him,  being  D.  furca  from  the 
Upper  Tremadoc.] 


376  CAMBRIAN  AND   SILURIAN  IN   EUROPE.  [XV. 

The  fauna  of  the  Tremadoc  slates  is,  according  to  Salter,  al- 
most entirely  distinct  from  that  of  the  Lingula  flags,  and  not 
less  distinct  from  that  of  the  so-called  Lower  Llandeilo  or 
Arenig  rocks  (the  equivalents  of  the  Skiddaw  slates  of  Cum- 
berland). Hence,  says  Ramsay,  it  is  evident  "that  in  these 
strata  we  have  three  perfectly  distinct  zones  of  organic  re- 
mains, and  therefore,  in  common  terms,  three  distinct  forma- 
tions." The  palseontological  evidence  is  thus  in  complete 
accordance  with  that  furnished  hy  stratigraphy.  "We  cannot 
leave  this  topic  without  citing  the  conclusion  of  Ramsay  that 
"each  of  these  two  breaks  necessarily  implies  a  lost  epoch, 
stratigraphically  quite  unrepresented  in  our  area;  the  life  of 
which  is  only  feebly  represented  in  some  cases  by  the  fossils 
common  to  the  underlying  and  overlying  formation."  In 
connection  with  this  remark,  which  we  conceive  to  embody 
a  truth  of  wide  application,  it  may  be  said  that  stratigraphical 
breaks  and  discordances  in  a  geological  series  may,  a  priori, 
be  expected  to  occur  most  frequently  in  regions  where  this 
series  is  represented  by  a  large  thickness  of  strata.  The  accu- 
mulation of  such  masses  implies  great  movements  of  subsi- 
dence, which,  in  their  nature,  are  limited,  and  are  accompa- 
nied by  elevations  in  adjacent  areas,  from  which  may  result, 
over  these  areas,  either  interruptions  in  the  process  of  sedi- 
mentation, or  the  removal,  by  sub-aerial  or  sub-marine  denuda- 
tion, of  the  sediments  already  formed.  The  conditions  of 
succession  and  distribution,  it  may  be  conceived,  would  be 
very  different  in  a  region  where  the  period  corresponding  to 
this  same  geological  series  was  marked  by  comparatively  small 
accumulations  of  sediment  upon  an  ocean-floor  subjected  to  no 
great  movements. 

This  contrast  is  strikingly  seen  between  the  conformable 
series  of  less  than  2,000  feet  of  strata,  which  in  Scandinavia 
are  characterized  by  the  first  three  palaeozoic  faunas  (Cambrian 
and  Silurian),  and  the  repeatedly  broken  and  discordant  suc- 
cession of  more  than  30,000  feet  of  sediments,*  which  in 

*  The  Longmynd  rocks  in  Shropshire  are  alone  estimated  at  20,000  feet  ; 
but  their  supposed  equivalents,  the  Harlech  rocks  of  Pembrokeshire,  have  a 


XV.]  CAMBRIAN  AND   SILURIAN  IN   EUROPE.  377 

"Wales  are  their  palseontological  equivalents.  It  must,  however, 
be  considered  that  in  regions  of  small  accumulation  where,  as 
in  Scandinavia,  the  formations  are  thin,  there  may  be  lost  or 
unrepresented  zoological  periods  whose  place  in  the  series  is 
marked  by  no  stratigraphical  break.  In  such  comparatively 
stable  regions,  movements  of  the  surface  sufficient  to  cause  the 
exclusion,  or  the  disappearance  by  removal,  of  the  small  thick- 
ness of  strata  corresponding  to  a  zoological  period,  may  take 
place  without  any  conspicuous  marks  of  stratigraphical  dis- 
cordance. 

The  attempt  to  establish  geological  divisions  or  horizons 
upon  stratigraphical  or  palaeontological  breaks  must  always 
prove  fallacious.  From  the  nature  of  things,  these,  whether 
due  to  non-deposition  or  to  subsequent  removal  of  deposits, 
must  be  local ;  and  we  can  say,  confidently,  that  there  exists 
no  break  in  life  or  in  sedimentation  which  is  not  somewhere 
filled  up  and  represented  by  a  continuous  and  conformable  suc- 
cession. While  we  may  define  one  period  as  characterized  by 
the  presence  of  a  certain  fauna,  which,  in  a  succeeding  age,  is 
replaced  by  a  different  one,  there  will  always  be  found,  in  some 
part  of  their  geographical  distribution,  a  region  where  the  two 
faunas  commingle,  and  where  the  gradual  disappearance  of  the 
old  before  the  new  may  be  studied.  The  division  of  our  strati- 
fied rocks  into  systems  is  therefore  unphilosophical,  if  we 
assign  any  definite  or  precise  boundaries  or  limitations  to  these. 
It  was  long  since  said  by  Sedgwick  with  regard  to  the  whole 
succession  of  life  through  geologic  time,  that  all  belongs  to 
one  great  systema  naturce.  (Philos.  Mag.  (4),  VIII.  359.) 

We  have  already  noticed  that  Barrande,  as  early  as  1852, 
gave  the  name  of  Primordial  Silurian  to  the  rocks  which,  in 

measured  thickness  of  3,300,  while  the  Llanberris  and  Harlech  rocks  to- 
gether, in  North  Wales,  equal  from  4,000  to  7,000  feet,  and  the  Lingula  flags 
and  Tremadoc  slates,  united,  about  7,000  feet.  The  Bala  group  in  the  Ber- 
wyns  exceeds  12,000  feet,  and  the  proper  Silurian,  from  the  base  of  the 
Upper  Llandovery  or  May  Hill  sandstone,  attains  from  5,000  to  6,000  feet ; 
so  that  the  aggregate  of  30,000  feet  may  be  considered  below  the  truth. 
(Mem.  Geol.  Survey,  III.,  Part  II.  pages  72,  222  ;  and  Siluria,  4th  ed.  185.) 
[The  aggregate  thickness  since  assigned  to  these  rocks  by  Hicks  is  about 
33,000  feet]  . 


378  CAMBRIAN  AND   SILURIAN   IN   EUROPE.  [XV. 

Bohemia,  were  marked  by  the  first  fauna  ;  although  he,  at  the 
same  time,  recognized  this  as  distinct  from  and  older  than  the 
second  fauna,  discovered  in  the  Llandeilo  rocks,  which  Murchi- 
son  had  declared  to  represent  the  dawn  of  organic  life.  Into 
the  reasons  which  led  Barrande  to  include  the  rocks  of  the 
first,  second,  and  third  faunas  in  one  Silurian  system  (a  view 
which  was  at  once  adopted  by  the  'British  Geological  Survey 
and  by  Murchison  himself),  it  is  not  our  province  to  inquire, 
but  we  desire  to  call  attention  to  the  fact  that  the  latter,  by 
his  own  principles,  was  bound  to  reject  such  a  classification. 
In  his  address  before  the  Geological  Society  in  1842  (already 
quoted  in  the  first  part  of  this  paper),  he  declared  that  the 
discussion  as  to  the  value  of  the  term  Cambrian  involved 
the  question  "  whether  there  was  any  type  of  fossils  in  the 
mass  of  the  Cambrian  rocks  different  from  those  of  the  Lower 
Silurian  series.  If  the  appeal  to  nature  should  be  answered  in 
the  negative,  then  it  was  clear  that  the  Lower  Silurian  type 
must  be  considered  the  true  base  of  what  I  had  named  the 
protozoic  rocks ;  but  if  characteristic  new  forms  were  discov- 
ered, then  would  the  Cambrian  rocks,  whose  place  was  so  well 
established  in  the  descending  series,  have  also  their  own  fauna, 
and  the  palaeozoic  base  would  necessarily  be  removed  to  a 
lower  horizon." 

In  the  event  of  no  distinct  fauna  being  found  in  the  Cam- 
brian series,  it  was  declared  that  "  the  term  Cambrian  must 
cease  to  be  used  in  zoological  classification,  it  being,  in  that 
sense,  synonymous  with  Lower  Silurian."  (Proc.  Geol.  Soc., 
III.  641,  et  seq.)  That  such  had  been  the  result  of  palaeon- 
tological  inquiry  Murchison  then  proceeded  to  show.  Inas- 
much as  the  only  portion  of  Sedgwick's  Cambrian  which  was 
then  known  to  be  fossiliferous  was  really  above,  and  not  be- 
low, the  Llandeilo  rocks,  which  Murchison  had  taken  for  the 
base  of  his  Lower  Silurian,  his  reasoning  with  regard  to  the 
Cambrian  nomenclature,  based  on  a  false  datum,  was  itself 
fallacious ;  and  it  might  have  been  expected  that  when  the 
government  surveyors  had  shown  his  stratigraphical  error, 
Murchison  would  have  rendered  justice  to  the  nomenclature  of 


XV.]  CAMBRIAN  AND   SILURIAN  IN  EUROPE.  379 

Sedgwick.  But  when,  still  later,  a  further  "  appeal  to  nature  " 
led  to  the  discovery  of  "  characteristic  new  forms,"  and  estab- 
lished the  existence  of  a  "  type  of  fossils  in  the  mass  of  the 
Cambrian  rocks,  different  from  those  of  the  Lower  Silurian 
series,"  Murchison  was  bound  by  his  own  principles  to  recog- 
nize the  name  of  Cambrian  for  the  great  Festiniog  group,  with 
its  primordial  fauna,  even  though  Barrande  and  the  govern- 
ment surveyors  should  unite  in  calling  it  Primordial  Silurian. 

He,  however,  chose  the  opposite  course,  and  now  attempted 
to  claim  for  the  Silurian  system  the  whole  of  the  Middle 
Cambrian  or  Festiniog  group  of  Sedgwick,  including  the  Tre- 
madoc  slates  and  the  Lingula  flags.  The  grounds  of  this 
assumption,  as  set  forth  in  the  successive  editions  of  Siluria 
from  1854  to  1867,  and  in  various  memoirs,  may  be  included 
under  three  heads  :  first,  that  the  Lingula  flags  have  been  found 
to  exist  in  some  parts  of  his  original  Silurian  region ;  second, 
that  no  clearly  defined  base  had  been  assigned  by  him  to  his 
so-called  system ;  and,  third,  that  there  are  no  means  of  draw- 
ing a  line  of  demarcation  between  those  Middle  Cambrian 
formations  and  the  overlying  Llandeilo. 

With  regard  to  the  first  of  these  reasons,  it  is  to  be  said 
that  the  only  known  representatives  of  the  Lingula  flags  in 
the  region  described  by  Murchison  in  his  Silurian  system  are 
the  black  slates  of  Malvern  and  some  scanty  outliers  which, 
in  Shropshire,  lie  between  the  old  Longmynd  rocks  and  the 
base  of  the  Stiper-stones.  The  former  were  then  (as  has  already 
been  shown)  supposed  by  him  to  belong  to  the  Llandeilo,  or 
rather  to  the  passage-beds  between  the  Llandeilo  and  the  Cam- 
brian (Bala) ;  while  with  regard  to  the  latter,  Ramsay  expressly 
tells  us  that  they  were  not  originally  classed  with  the  Silurian, 
but  have  since  been  included  in  it.  (Mem.  Geol.  Sur.,  III. 
Part  II.  page  9  ;  and  242,  foot-note.) 

The  Llandeilo  beds  were  by  Murchison  distinctly  stated  to 
be  the  base  of  the  Silurian  system  (Silurian  System,  222) ; 
and  it  was  further  declared  by  him  that  in  Shropshire  (unlike 
Caermarthenshire)  "  there  is  no  passage  from  the  Cambrian  to 
the  Silurian  strata,"  but  a  hiatus,  marked  by  disturbances 


380  CAMBRIAN   AND   SILURIAN   IN  EUROPE.  [XV. 

which  excluded  the  passage-beds,  and  caused  the  Lower  Silu- 
rian to  rest  unconforaiably  upon  the  Longrnynd  rocks.  (Ibid., 
256  ;  and  Plate  31,  sections  3  and  6  ;  Plate  32,  section  4.)  But 
in  Siluria  (1st  ed.  47)  the  two  are  stated  to  be  conformable ; 
and  in  the  subsequent  sections  of  this  region,  made  by  Aveline, 
and  published  by  the  Geological  Survey,  the  evidences  of  this 
want  of  conformity  do  not  appear.  Murchison  at  that  time 
confounded  the  rocks  of  the  Longmynd  with  the  Cambrian 
(Bala)  beds  of  Caermarthenshire  and  Brecon.  (Silurian  Sys- 
tem, 416.)  Hence  it  was  that  he  gave  the  name  of  Cambrian 
to  the  former;  and  this  mistake,  moreover,  led  him  to  place 
the  Cambrian  of  Caermarthenshire  beneath  the  Llandeilo.  It 
is  clear  that  if  he  claimed  no  well-defined  base  to  the  Llandeilo 
rocks  in  this  latter  (their  typical  region),  it  was  because  he  saw 
them  passing  into  the  overlying  Bala  beds.  There  was,  in  the 
error  by  which  he  placed  below  the  Llandeilo,  strata  which 
were  really  above  them,  no  ground  whatever  for  afterwards 
including  in  his  Silurian  System,  as  a  downward  continuation 
of  the  Llandeilo  rocks  (which  are  the  basal  portion  of  the  Bala 
group),  the  whole  Festiniog  group  of  Sedgwick ;  whose  infra- 
position  to  the  Bala  had  been  shown  by  the  latter  long  before 
it  was  known  to  be  fossiliferous. 

It  was,  however,  claimed  by  Murchison  that  no  line  of  sepa- 
ration can  be  drawn  between  these  two  groups.  The  results  of 
Ramsay  and  of  Salter,  as  set  forth  in  the  address  of  the  former 
before  the  Geological  Society  of  1863,  and  more  fully  in  the 
Memoirs  of  the  Geological  Survey  (Vol.  III.  Part  II.)  published 
in  1866,  with  a  preface  by  himself,  as  the  director  of  the  Sur- 
vey, are  completely  ignored  by  Murchison.  The  reader  famil- 
iar with  these  results,  of  which  we  have  given  a  summary, 
finds  with  surprise  that  in  the  last  edition  of  Siluria,  that  of 
1867,  they  are  noticed  in  part,  but  only  to  be  repudiated.  In 
the  five  pages  of  text  which  are  there  given  to  this  great  Mid- 
dle Cambrian  division,  we  are  told  that  the  distinction  between 
the  Lower  Tremadoc  and  the  Lingula  flags  "  is  difficult  to  be 
drawn,"  and  that  the  Upper  Tremadoc  slate  passes  into  and 
forms  the  lower  part  of  the  Llandeilo  (under  which  name 


XV.]  CAMBRIAN  AND  SILURIAN   IN  EUROPE.  381 

Murchison  included  the  Arenig  rocks),  "  into  which  it  gradu- 
ates conformably."  (Loc.  cit.,  4th  ed.  p.  46.)  In  each  of  these 
cases,  on  the  contrary,  according  to  Ramsay,  there  is  observed 
"  a  break  very  nearly  complete  both  in  genera  and  species,  and 
probable  unconformity " ;  the  evidence  of  the  pala3ontological 
break  being  furnished  by  the  careful  studies  of  Salter ;  while 
that  of  the  stratigraphical  break,  as  we  have  seen,  leaves  no 
reason  for  doubt.  (Mem.  Geol.  Sur.,  III.  Part  II.  pages  2,  161, 
234.)  The  student  of  Siluria  soon  learns  that  in  all  cases 
where  Murchison's  pretensions  were  concerned,  the  book  is 
only  calculated  to  mislead. 

The  reader  of  this  history  will  now  be  able  to  understand 
why,  notwithstanding  the  support  given  by  Barrande,  by  the 
geological  survey  of  Great  Britain,  and  by  most  American 
geologists  to  the  Silurian  nomenclature  of  Murchison,  it  is 
rejected,  so  far  as  the  Lingula  flags  and  the  Tremadoc  slates 
are  concerned,  by  Lyell,  Phillips,  Davidson,  Harkness,  and 
Hicks  in  England,  and  by  Linnarsson  in  Sweden.  These 
geologists  have,  however,  admitted  the  name  of  Lower  Silu- 
rian for  the  Bala  group  or  Upper  Cambrian  of  Sedgwick;  a 
concession  which  can  hardly  be  defended,  but  which  appar- 
ently found  its  way  into  use  at  a  time  when  the  yet  unravelled 
perplexities  of  the  Welsh  rocks  led  Sedgwick  himself  to  pro- 
•pose,  for  a  time,  the  name  of  Cambro-Silurian  for  the  Bala 
group.  This  want  of  agreement  among  geologists  as  to  the 
nomenclature  of  the  lower  palaeozoic  rocks,  causes  no  little 
confusion  to  the  learner.  We  have  seen  that  Henry  Darwin 
Piogers  followed  Sedgwick  in  giving  the  name  of  Cambrian  to 
the  whole  palaeozoic  series  up  to  the  base  of  the  May  Hill 
sandstone ;  and  the  same  view  is  adopted  by  Woodward  in  his 
Manual  of  the  Mollusca.  The  student  of  this  excellent  book 
will  find  that  in  the  tables  giving  the  geological  range  of  the 
mollusca,  on  pages  124,  125,  and  127,  the  name  of  Cambrian 
is  used  in  Sedgwick's  sense,  as  including  all  the  fossiliferous 
strata  beneath  the  May  Hill  sandstone.  On  page  123  it  is, 
however,  explained  that  Lower  Silurian  is  a  synonyme  for  Cam- 
brian, and  it  is  so  used  in  the  body  of  the  work. 


382  CAMBRIAN  AND   SILURIAN   IN   EUROPE.  [XV. 

The  distribution  of  the  Lower  and  Middle  Cambrian  rocks 
in  Great  Britain  may  now  be  noticed.  The  former,  or  Bangor 
group,  to  which  Murchison  and  the  geological  survey  restrict 
the  name  of  Cambrian,  and  which  they  sometimes  call  the 
Longmynd,  bottom  or  basement  rocks,  occupy  two  adjacent 
areas  in  Caernarvon  and  Merionethshire ;  the  one  near  Bangor, 
including  Llanberris,  to  the  northeast,  and  the  other,  including 
Harlech  and  Barmouth,  to  the  southeast,  of  Snowdon;  this 
mountain  lying  in  a  synclinal  between  them,  and  rising  3,571 
feet  above  the  sea.  The  great  mass  of  grits  or  sandstones  ap- 
pears to  be  at  the  summit  of  the  group,  but  in  the  lower  part 
the  blue  roofing-slates  of  Llanberris  are  interstratified  in  a  series 
of  green  and  purple  slates,  grits,  and  conglomerates.  (Some 
of  the  Welsh  roofing-slates  are,  however,  supposed  to  belong 
to  the  Llandeilo.  Mem.  Geol.  Survey,  III.  Part  II.  pages  54, 
258.)  The  Harlech  rocks  in  this  northwestern  region  are  con- 
formably overlaid  by  the  Menevian,  followed  by  the  true 
Lingula  flags,  or  Olenus  beds,  of  the  Middle  Cambrian.  Upon 
these  repose  the  Tremadoc  slates. 

The  third  area  of  Lower  Cambrian  rocks  known  in  Great 
Britain  is  that  already  described  at  St.  David's  in  Pembroke- 
shire, about  one  hundred  miles  to  the  southwest ;  and  the 
fourth,  that  of  the  Longmynd  hills,  about  sixty  miles  to  the 
southeast  of  Snowdon.  The  rocks  of  the  Longmynd,  like ' 
those  of  the  other  Lower  Cambrian  areas  mentioned,  consist 
principally  of  green  and  purple  sandstones  with  conglomerates, 
shales,  and  some  clay-slates.  They  occasionally  hold  flakes  of 
anthracite,  and  small  portions  of  mineral  pitch  exude  from 
them  in  some  localities.  The  only  evidence  of  animal  life  yet 
found  in  the  rocks  of  the  Longmynd  are  furnished  by  worm- 
burrows,  the  obscure  remains  of  a  crustacean  (Palceopyge  Ram- 
say), and  a  form  like  Histioderma.  This  latter  organic  relic, 
with  worm-burrows,  and  the  fossils  named  Oldhamia,  is  found 
on  the  coast  of  Ireland  opposite  Caernarvonshire,  in  the  rocks 
of  Bray  Head ;  which  resemble  lithologically  the  Harlech 
beds,  and  are  regarded  as  their  equivalents. 

Still  another  area  of  the  older  rocks  is  that  of  the  Malvern 


XV.]  CAMBRIAN  AND   SILURIAN  IN  EUROPE.  '    383 

hills,  on  the  western  flanks  of  which,  as  already  mentioned, 
the  Lingula  flags  are  represented  by  about  500  feet  of  black 
shales  with  Olenus,  underlaid  by  600  feet  of  greenish  sand- 
stones containing  traces  of  fucoids,  with  Serpuiites  and  an 
Obolella.  It  is  not  improbable,  as  suggested  by  Barrande  and 
by  Murchison,  that  these  1,100  feet  of  strata  represent,  in  this 
region,  the  great  mass  of  the  Lingula  flags  ;  and,  we  may  add, 
perhaps,  the  whole  series  of  Lower  Cambrian  strata,  which  in 
Caernarvon  and  Pembroke  underlie  them  [see  page  371] ;  since 
these  sandstones  of  Malvern,  like  those  of  St.  David's,  rest  upon 
crystalline  schists,  and  are  in  part  made  up  of  their  ruins. 

These  crystalline  schists  of  Malvern,  which  are  described  by 
Phillips  as  the  oldest  rocks  in  England,  and  by  Mr.  Holl  are 
conjectured  to  be  Laurentian,  seem  from  the  descriptions  of 
their  lithological  characters  to  resemble  those  of  Caernarvon 
and  Anglesea,  with  which  they  are,  by  Murchison,  regarded  as 
identical  The  crystalline  schists  of  these  latter  localities  are, 
by  Sedgwick,  described  as  hypozoic  strata,  below  the  base  of  t 
the  Cambrian.  Murchison,  however,  in  the  first  edition  of  his 
Siluria,  adopted  the  suggestion  of  De  la  Beche  that  they  them- 
selves were  altered  Cambrian  strata.  In  fact,  they  directly 
underlie  the  Llandeilo  rocks,  and  were  apparently  conceived  by 
Murchison  to  represent  that  downward  continuation  of  these 
upon  which  he  had  insisted.  This  opinion  is  supported  by 
ingenious  arguments  on  the  part  of  Ramsay.  (Mem.  Geol. 
Survey,  III.  Part  II.,  passim.)  I  am,  however,  disposed  to 
regard  them,  with  Sedgwick  and  Phillips,  as  of  pre-Cambrian 
age,  and  to  compare  them  with  the  Huronian  series  of  North 
America,  which  occupies  a  similar  geological  horizon,  and  with 
which,  as  seen  in  northern  Michigan,  and  in  the  Green  Moun- 
tains, I  have  found  the  rocks  of  Anglesea  to  offer  remarkable 
lithological  resemblances. 

It  may  here  be  noticed  that  the  gold-bearing  quartz  veins  in 
North  Wales  are  found  in  the  Menevian  beds,  and  also,  accord- 
ing to  Selwyn,  throughout  the  Lingula  flags.  These  fossilifer- 
ous  strata  at  the  gold-mine  near  Dolgelly  appear  in  direct  con- 
tact with  diorites  and  chloride  and  talcose  schists,  which  are 


384  CAMBRIAN  AND   SILURIAN  IN   EUROPE.  [XV. 

more  or  less  cupriferous,  and  themselves  also  contain  gold-bear- 
ing quartz  veins.  (Mem.  Geol.  Survey,  Part  II.  pages  42,  45 ; 
and  Siluria,  4th  ed.  450,  547.) 

The  Table  on  page  386  gives  a  view  of  the  lower  palaeozoic 
rocks  of  Great  Britain  and  North  America,  together  with  the 
various  nomenclatures  and  classifications  referred  to  in  the  pre- 
ceding pages.  In  the  second  column,  the  horizontal  black 
lines  indicate  the  positions  of  the  three  important  pala3ontologi- 
cal  and  stratigraphical  breaks  signalized  by  Earn  say  in  the 
British  succession.  (Mem.  Geol.  Survey,  III.  Part  II.  page  2.) 

[Very  recently,  in  1873,  in  the  Proceedings  of  the  Geolo- 
gists' Association,  Vol.  III.  Part  III.,  Mr.  Hicks  has  given  ya 
similar  tabular  view  of  the  lower  palaeozoic  rocks  of  Great  Brit- 
ain. The  Bangor  group  (to  which  he  applies  the  name  of  Long- 
mynd  or  Lower  Cambrian), differs  from  that  given  in  the  follow- 
ing table  only  in  dividing  the  Menevian  into  an  upper  and  a 
lower  part.  The  Middle  Cambrian  or  Festiniog  group  of  Sedg- 
,wick  (which  Hicks  calls  Upper  Cambrian)  presents  also  the 
same  subdivisions  as  are  here  given.  In  the  next,  or  Upper 
Cambrian  of  Sedgwick  (called  by  Hicks  Lower  Silurian),  are  in- 
cluded in  ascending  order  Lower  Areuig  and  Upper  Arenig  or 
Skiddaw,  followed  by  Llandeilo,  also  divided  into  two  parts, 
and  by  the  Bala  group,  which  he  divides  into  Lower  and 
Upper  Caradoc,  to  which  he  adds,  as  we  have  done,  the  Lower 
Llandovery.] 

[In  the  new  Catalogue  of  the  Cambridge  Fossils  is  an  impor- 
tant preface  written  from  Sedgwick's  dictation  late  in  1872, 
and  published  since  his  death.  In  this  he  unites  the  Lower 
Llandovery  with  the  Upper  Cambrian,  and  includes  it,  together 
with  the  Caradoc  and  Llandeilo,  under  the  name  of  the  Bala 
group,  which  he  divides  into  Lower,  Middle,  and  Upper  Bala ; 
while  the  Arenig  or  Skiddaw  rocks  are  joined  with  the 
Middle  Cambrian.  Both  the  Arenig  and  the  Tremadoc  rocks, 
in  fact,  present  a  certain  intermingling  of  organic  forms  belong- 
ing to  the  first  and  second  faunas  ;  but  according  to  Hicks  the 
Tremadoc  beds  are  to  be  classed  with  the  first,  and  the  Arenig 
with  the  second.  These  two  groups  of  rocks  are  in  fact  the 


XV.]  CAMBRIAN   AND   SILURIAN  IN  EUROPE.  385 

palaeontological  equivalents  of  the  Calciferous,  Levis  and  Chazy, 
which  serve  in  North  America  to  connect  the  Middle  with 
the  Upper  Cambrian.  As  regards  the  extension  to  the  Upper 
Cambrian  of  Sedgwick  of  the  name  of  Lower  Silurian,  which, 
as  has  been  shown,  was  given  to  it  only  through  an  enormous 
and  now  universally  acknowledged  mistake  on  the  part  of 
Murchison,  I  am  constrained,  notwithstanding  its  adoption  by  so 
many  eminent  geologists,  to  maintain  for  the  division  the  name 
given  to  it  by  its  true  discoverer,  Sedgwick.] 

In  the  third  column,  the  subdivisions  are  those  of  the  New 
York  and  Canada  Geological  Surveys ;  in  connection  with 
which  the  reader  is  referred  to  a  table  which  I  prepared  and 
published  in  1863,  in  the  Geology  of  Canada,  page  932.  Op- 
posite to  the  Menevian  I  have  placed  the  names  of  its  principal 
American  localities ;  which  are  Braintree,  Massachusetts,  St. 
John,  New  Brunswick,  and  St.  John's,  Newfoundland.  The 
further  consideration  of  the  American  subdivisions  is  reserved 
for  the  third  part  of  this  paper.  With  regard  to  the  classification 
of  Angelin,  it  is  to  be  remarked  that  although  he  designates  II. 
as  Regio  Olenorum,  and  III.  as  Regio  Conocorypharum,  the 
position  of  these,  according  to  Linnarsson,  is  to  be  reversed ; 
the  Conocoryphe  beds  with  Paradoxides  being  below,  and  not 
above,  those  holding  Olenus.  The  Regio  Fucoidarum  in 
Sweden  has  lately  furnished  a  brachiopodous  shell,  Lingula 
monilifera,  besides  the  curious  plant-like  fossil,  Eophyton 
Linnceanum.  (Liimarsson,  Geol.  Magazine,  1869,  VI.  393.) 


17 


386 


CAMBRIAN  AND   SILURIAN  IN   EUROPE. 


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XV.]       CAMBRIAN   AND   SILURIAN  IN   NORTH   AMERICA.      387 


III.   CAMBRIAN  AND  SILURIAN  EOCKS  IN  NORTH  AMERICA. 

In  accordance  with  our  plan  we  now  proceed  to  sketch  the 
history  of  the  lower  palaeozoic  rocks  of  North  America.  While 
European  geologists  were  carrying  out  the  researches  which 
have  been  described  in  the  first  and  second  parts  of  this  paper, 
American  investigators  were  not  idle.  The  geological  studies 
of  Eaton  led  the  way  to  a  systematic'  survey  of  the  State  of 
New  York,  the  results  of  which  have  been  the  basis  of  most 
of  the  subsequent  geological  work  in  eastern  North  America, 
and  which  was  begun  by  legislative  enactment  in  1836.  The 
State  was  divided  into  four  districts,  the  work  of  examining 
and  finally  reporting  upon  which  was  committed  to  as  many 
geologists.  The  first  or  southeastern  district  was  undertaken 
by  Mather,  the  second  or  northeastern  by  Emmons,  the  third 
or  central  by  Yanuxem,  and  the  fourth  or  western  by  James 
Hall ;  the  paleontology  of  the  whole  being  left  to  Conrad,  and 
the  mineralogy  to  Beck.  After  various  annual  reports  the 
final  results  of  the  survey  appeared  in  1842.  The  whole  series 
of  fossiliferous  rocks  known,  from  the  basal  or  Potsdam  sand- 
stone to  the  coal-formation,  was  then  described  as  the  New 
York  system. 

At  that  time  the  published  researches  of  British  geologists 
furnished  the  means  of  comparison  between  the  organic  remains 
found  in  the  rocks  of  New  York,  and  those  then  known  to 
exist  in  the  palaeozoic  strata  of  Great  Britain.  Professor  Hall 
was  thus  enabled,  in  his  Geology  of  the  Fourth  District  of  New 
York,  to  declare,  from  the  study  of  its  fossils,  that  the  New 
York  system  included  the  Devonian  of  Phillips,  the  Silurian 
of  Murchison,  and  the  Cambrian  of  Sedgwick;  meaning  by 
the  latter  the  Upper  Cambrian,  or  Bala  group,  which  alone 
was  then  known  to  be  fossiliferous.  From  the  evidence  then 
before  him,  he  concluded  that  the  Upper  Cambrian  was  repre- 
sented in  the  New  York  system  by  the  whole  of  the  rocks  from 
the  base  of  the  Utica  slate  downward,  with  the  probable  ex- 
ception of  the  Potsdam  sandstone ;  while  he  conceived,  partly 


388      CAMBRIAN  AND  SILURIAN  IN  NORTH  AMERICA.       [XV. 

on  lithological  grounds,  that  the  Utica  and  Hudson-  Eiver 
groups  represented  the  Llandeilo  and  Caradoc,  or  the  Lower 
Silurian  of  Murchison.  (Loe.  cit.,  pages  20,  29,  31.)  The  origin 
of  the  Cambrian  and  Silurian  controversy,  and  the  errors  by 
which  the  Llandeilo  and  a  part  of  the  Caradoc  had  by  Murchi- 
son been  classed  as  a  series  distinct  from  the  Bala  group,  were 
not  then  known  ;  but  in  a  note  to  this  report  (page  20)  Hall 
informs  us  of  the  declaration  of  Murchison,  already  quoted 
from  his  address  of  1842,  that  the  Cambrian,  so  far  as  then 
known,  could  not,  on  palseontological  grounds,  be  distinguished 
from  his  Lower  Silurian. 

Emmons  meanwhile  had  examined  in  eastern  New  York 
and  western  New  England  a  series  of  fossiliferous  rocks  which, 
on  lithological  and  stratigraphical  grounds,  he  regarded  as 
older  than  any  in  the  New  York  system ;  a  view  which  had 
been  previously  maintained  by  Eaton.  Holding,  with  Hall, 
that  the  lower  members  of  the  New  York  system  were  the 
equivalents  of  the  Upper  Cambrian  of  Sedgwick,  he  looked 
upon  the  fossiliferous  rocks  which  he  placed  beneath  them  as 
the  representatives  of  the  Lower  Cambrian.  By  this  name,  as 
we  have  seen,  Sedgwick,  in  1838,  designated  all  those  un- 
crystalline  rocks  of  North  Wales  which  he  subsequently  divided 
into  Lower  and  Middle  Cambrian,  and  which  lie  beneath  the 
base  of  the  Bala  group.  When  Murchison,  in  1842,  in  his  so 
often  quoted  declaration,  asserted  that  "  the  term  Cambrian  must 
cease  to  be  used  in  a  zoological  classification,  it  being  in  that 
sense  synonymous  with  Lower  Silurian,"  he  was  speaking  only 
on  palaBontological  grounds,  and,  disregarding  the  great  Lower 
and  Middle  Cambrian  divisions  of  Sedgwick,  had  reference  only 
to  the  Upper  Cambrian.  This,  however,  was  overlooked  by 
Emmons,  who,  feeling  satisfied  that  the  sedimentary  rocks  which 
he  had  examined  in  eastern  New  York  were  distinct  from  those 
which  he,  with  Hall,  regarded  as  corresponding  to  the  Bala 
group  or  Upper  Cambrian  (the  Lower  Silurian  of  Murchison), 
and  probably  equivalent  to  the  inferior  portions  of  Sedgwick's 
Cambrian  ;  and,  supposing  that  the  latter  term  was  henceforth 
to  be  effaced  from  geology  (as  indeed  was  attempted  shortly 


XV.]      CAMBRIAN  AND   SILURIAN  IN   NORTH   AMERICA.      389 

after,  in  the  copy  of  Sedgwick's  map  published  in  1844  by  the 
Geological  Society),  devised  for  these  rocks  the  name  of  the 
Taconic  system,  as  synonymous  with  the  Lower  (and  Middle) 
Cambrian  of  Sedgwick.  These  conclusions  were  set  forth  by 
him  in  1842,  in  his  report  on  the  Geology  of  the  Northern 
District  of  New  York  (page  162).  See  farther  his  Agriculture 
of  New  York  (I.  49),  the  fifth  chapter  of  which,  "  On  the 
Taconic  System,"  was  also  published  separately  in  1844  ;  when 
the  presence  of  distinctive  organic  remains  in  the  rocks  of 
this  series  was  first  announced. 

Meanwhile  to  Professor  Hall,  after  the  completion  of  the 
survey,  had  been  committed  the  task  of  studying  and  describ- 
ing the  organic  remains  of  the  State,  and  in  1847  appeared 
the  first  volume  of  his  great  work  on  the  Palaeontology  of  New 
York.  Since  1842  he  had  been  enabled  to  examine  more 
fully  the  organic  remains  of  the  lower  rocks  of  the  New  York 
system,  and  to  compare  them  with  those  of  the  Old  World  ; 
and  in  the  Introduction  to  the  volume  just  mentioned  (page 
xix)  he  announced  the  important  conclusion  that  the  New  York 
system  itself  contained  an  older  fauna  than  the  Upper  Cam- 
brian of  Sedgwick.  According  to  Hall,  the  organic  forms  of 
the  Calciferous  and  Chazy  formations  had  not  yet  been  found 
in  Europe,  and  our  comparison  with  European  fossiliferous 
rocks  must  commence  with  the  Trenton  group.  He  however 
excepted  the  Potsdam  sandstone,  which  already,  in  1842,  he 
had  conceived  to  be  "below  the  Upper  Cambrian  of  Sedgwick, 
and  now  regarded  as  the  probable  equivalent  of  the  Obolus 
or  Ungulite  grit  of  St.  Petersburg.  Thus  Emmons,  in  1842, 
asserted,  on  lithological  and  stratigraphical  grounds,  the  exist- 
ence, beneath  the  base  of  the  New  York  system,  of  a  lower 
and  uiiconformable  series  of  rocks,  in  which,  in  1844,  he  an- 
nounced the  discovery  of  a  distinctive  fauna.  Hall,  on  his 
part,  asserted  in  1842,  and  more  fully  in  1847,  that  the  New 
York  system  itself  held  an  older  fauna  than  that  hitherto 
known  in  the  British  rocks. 

It  is  not  necessary  to  recall  in  this  place  the  details  of  the 
long  and  unfortunate  Taconic  controversy,  t  which  I  have  re- 


390      CAMBRIAN  AND  SILURIAN  IN   NORTH  AMERICA,      [XV. 

cently  discussed  in  my  address  before  the  American  Associa- 
tion for  the  Advancement  of  Science  in  August,  1871.  (Ante, 
page  251.)  It  is,  however,  to  be  remarked  that  Hall,  in  com- 
mon with  all  other  American  geologists,  followed  Henry  D. 
Rogers  in  opposing  the  views  of  Emmons,  whose  Taconic 
system  was  supposed  to  represent  either  the  whole  or  a  part 
of  the  Champlain  division  of  the  New  York  system ;  which 
division  included,  as  is  well  known,  all  of  the  fossiliferous 
rocks  up  to  the  base  of  the  Oneida  conglomerate  (and  also  this 
latter,  according  to  Emmons) ;  thus  comprehending  both  the 
first  and  the  second  palaeozoic  faunas ;  as  shown  in  the  pre- 
ceding table  on  page  386. 

Emmons,  misled  by  stratigraphical  and  lithological  consider- 
ations, complicated  the  question  in  a  singular  manner,  which 
scarcely  finds  a  parallel  except  in  the  history  of  Murchison's 
Silurian  sections.  Completely  inverting,  as  I  have  elsewhere 
shown,  the  order  of  succession  in  his  Taconic  system,  estimated 
by  him  at  30,000  feet,  he  placed  near  the  base  of  the  lower 
division  of  the  system  the  Stockbridge  or  Eolian  limestone,  in- 
cluding the  white  marbles  of  Vermont ;  which,  l?y  their  organic 
remains,  have  since  been  by  Billings  found  to  belong  to  the 
Levis  formation.  A  large  portion  of  the  related  rocks  in 
western  Vermont  and  elsewhere,  which  afford  a  fauna  now 
known  to  be  far  more  ancient  than  that  of  the  Lower  Taconic 
just  referred  to,  and  as  low  if  not  lower  than  anything  in  the 
New  York  system,  were,  by  Emmons,  then  placed  partly  near 
the  summit  of  the  Upper  Taconic,  and  partly,  not  only  above 
the  whole  Taconic  system,  but  above  the  Champlain  division 
of  the  New  York  system.  Thus  we  find,  in  1842,  in  his  Re- 
port on  the  Geology  of  the  Northern  District  of  New  York 
(where  Emmons  defined  his  views  on  the  Taconic  system), 
that  he  placed  above  this  latter  horizon  both  the  green  sand- 
stone of  Sillery  near  Quebec  and  the  Red  sand-rock  of  western 
Vermont  (which  he  then  regarded  as  the  representatives  of 
the  Oneida  and  the  Medina  sandstones),  and  described  the 
latter  as  made  up  from  the  ruins  of  Taconic  rocks  (pages  124, 
282).  In  1844-1846,  in  his  Report  on  the  Agriculture  of 


XV.]      CAMBRIAN  AND  SILURIAN  IN   NORTH  AMERICA.      391 

New  York  (page  119),  he  however  adopted  a  different  view  of 
the  Red  sand-rock,  assigning  it  to  the  Calciferous ;  and  in  1855, 
in  his  American  Geology  (II.  128),  it  was  regarded  as  in  part 
Calciferous  and  in  part  Potsdam.  In  1848,  Professor  C.  B. 
Adams,  then  director  of  the  Geological  Survey  of  Vermont, 
argued  strongly  against  these  latter  views,  and  maintained  that 
the  Red  sand-rock  directly  overlaid  the  shales  of  the  Hudson- 
River  group  and  corresponded  to  the  Medina  and  Clinton  for- 
mations of  the  New  York  system.  (Amer.  Jour.  ScL  (2),  Y. 
108.)  He  had  "before  this  time  discovered  in  this  sand-rock, 
besides  what  he  considered  an  Atrypa,  abundant  remains  of  a 
trilobite,  which  Hall,  in  1847,  referred  to  the  genus  ConocepJialus 
(Conocoryphe),  remarking  at  the  same  time  that  inasmuch  as 
this  genus  was  (at  that  time)  only  described  as  occurring  in 
"  gray  wacke  in  Germany  and  elsewhere,"  no  conclusions  could 
be  drawn  from  these  fossils  as  to  the  geological  horizon  of  the 
rocks  in  question.  (Ibid.  (2),  XXXIII.  371.)  In  September, 
1861,  however,  Mr.  Billings,  after  an  examination  of  the  rocks 
in  question,  pronounced  in  favor  of  the  later  opinion  of  Em- 
mons,  declaring  the  Red  sand-rock  near  Highgate  Springs, 
Vermont,  containing  Conocephalus  and  Theca,  to  belong  to  the 
base  of  the  second  fauna,  "  if  not  indeed  a  little  lower,"  and 
to  be  "  somewhere  near  the  horizon  of  the  Potsdam."  (Ibid. 
(2),  XXXII.  232.) 

The  dark-colored  fossiliferous  shales  which  were  asserted, 
both  by  Adams  and  by  Emmons,  to  underlie  this  Red  sand- 
rock,  were,  by  the  former,  as  we  have  seen,  regarded  as  belong- 
ing to  the  Hudson-River  group,  while  by  the  latter  they  were 
described  as  an  upper  member  of  the  Taconic  system ;  which 
was  here  declared  to  be  unconformably  overlaid  by  the  Red 
sand-rock,  a  member  of  the  New  York  system.  These  slates, 
a  few  years  before,  had  afforded  some  trilobites,  which,  after 
remaining  in  the  hands  of  Professor  Hall  for  two  years  or 
more,  were  in  1859  described  by  him  in  the  twelfth  Report 
of  the  Regents  of  the  University  of  New  York,  as  Olenus 
Thompsoni  and  0.  Vermontana.  He  soon,  however,  found 
them  to  constitute  a  distinct  genus,  for  which  he  proposed  the 


392      CAMBRIAN  AND   SILURIAN  IN  NORTH   AMERICA.       [XV. 

name  of  Barrandia,  but  finding  this  name  preoccupied,  suggested 
in  1861,  in  the  fourteenth  Regents'  Report,  that  of  Olenellus, 
which  was  subsequently  adopted  by  Billings  in  1865.  (Palaeo- 
zoic Fossils,  pages  365,  419.)  In  1860,  Emmons,  in  his  Manual 
of  Geology,  described  the  same  species,  but  placed  them  in  the 
genus  Paradoxides,  as  P.  Thompsoni  and  P.  Vermontana.  Hall 
had  already,  in  1847,  in  the  first  volume  of  his  Palaeontology 
of  New  York,  referred  to  Olenus  the  Elliptocephalus  asaphoides 
of  Emmons,  and  also  a  fragment  of  another  trilobite  from 
Saratoga  Lake  ;  both  of  which  were  described  as  belonging  to 
the  Hudson-River  group  of  the  New  York  system,  or  to  a  still 
higher  horizon.  The  reasons  for  this  will  appear  in  the  sequel. 
The  Elliptocephalus,  with  another  trilobite  named  by  Emmons 
Atops  (referred  by  Hall  to  Calymene,  and  subsequently  by  Bil- 
lings to  Conocoryphe),  occurs  at  Greenwich,  New  York.  These 
were  by  Emmons,  in  his  essay  on  the  Taconic  system  (in  1844), 
described  as  characteristic  of  that  system  of  rocks. 

A  copy  of  the  Regents'  Report  for  1859  having  been  sent  by 
Billings  to  Barrande,  this- eminent  palaeontologist,  in  a  letter 
addressed  to  Professor  Bronn  of  Heidelberg,  July  16,  1860 
(American  Journal  of  Science  (2),  XXXI.  212),  called  attention 
to  the  trilobites  therein  figured,  and  declared  that  no  palaeon- 
tologist familiar  with  the  trilobites  of  Scandinavia  would  "  have 
hesitated  to  class  them  among  the  species  of  the  primordial 
fauna,  and  to  place  the  schists  enclosing  them  in  one  of  the 
formations  containing  this  fauna.  Such  is  my  profound  convic- 
tion," etc.  The  letter  containing  this  statement  had  already 
appeared  in  the  American  Journal  of  Science  for  March,  1861, 
but  Mr.  Billings  in  his  note  just  referred  to,  on  the  fossils  of 
Highgate,  in  the  same  Journal  for  September  of  that  year, 
makes  no  allusion  to  it.  In  March,  1862,  however,  he  re- 
turns to  the  subject  of  the  sand-rock,  in  a  more  detailed  commu- 
nication (Ibid.  (2),  XXXIII.  100),  and  after  correcting  some 
omissions  in  his  former  note,  alludes  in  the  following  language 
to  Mr.  Barrande,  and  to  the  expressed  opinion  of  the  latter, 
just  quoted,  with  regard  to  the  fossils  in  question  and  the 
rocks  containing  them  :  "  I  must  also  state  that  Barrande  first 


XV.]       CAMBRIAN  AND   SILURIAN  IN  NORTH   AMERICA.      393 

determined  the  age  of  the  slates  in  Georgia,  Vermont,  holding 
P.  Thompsoni  and  P.  Vermontana"  He  adds,  " at  the  time  I 
wrote  the  note  on  the  Highgate  fossils  it  was  not  known  that 
these  slates  were  conformably  interstratified  with  the  Red  sand- 
rock.  This  discovery  was  made  afterwards  by  the  Rev.  J.  B. 
Ferry  and  Dr.  G.  M.  Hall  of  S wanton." 

Air.  Billings  has  blamed  me  (Canadian  Naturalist,  new  series, 
VI.  318)  for  having  written  in  1871  (ante,  page  258),  with 
regard  to  the  Georgia  trilobites  first  described  as  Oleinis  by 
Professor  Hall,  that  Barrande  "called  attention  to  their  pri- 
mordial character,  and  thus  led  to  a  knowledge  of  their  true 
stratigraphical  horizon."  I  had  always  believed  that  the  letter 
of  Barrande  and  the  explicit  declaration  of  Mr.  Billings,  just 
quoted,  contained  the  whole  truth  of  the  matter.  My  atten- 
tion has  since  been  called  to  a  subsequent  note  by  Air.  Billings 
in  May,  1862  (Ibid  (2),  XXXIII.  421),  in  which,  while  as- 
serting that  Emmons  had  already  assigned  to  these  rocks  a 
greater  age  than  the  New  York  system,  he  mentions  that  in 
sending  to  Barrande,  in  the  spring  of  1860,  the  report  of  Pro- 
fessor Hall  on  the  Georgia  fossils,  he  alluded  to  their  primordial 
character,  and  suggested  that  they  might  belong  to  what  Mr. 
Barrande  has  called  "  a  colony "  in  the  rocks  of  the  second 
fauna.  This  is  also  stated  in  a  note  by  Sir  William  Logan  in 
the  Preface  to  the  Geology  of  Canada  (page  viii).  As  the 
genus  Olenus,  to  which  Professor  Hall  had  referred  the  fossils 
in  question,  was  at  that  time  (1860)  well  known  to  belong, 
both  in  Great  Britain  and  in  Scandinavia,  to  the  primordial 
fauna,  Mr.  Barrande  does  not  seem  to  have  thought  it  neces- 
sary in  his  correspondence  to  refer  to  the  very  obvious  remark 
of  Mr.  Billings. 

Mr.  Billings  further  showed  in  his  paper  in  March,  1862, 
that  fossils  identical  with  those  of  the  Georgia  slates  had  been 
found  by  him  in  specimens  collected  by  Mr.  Richardson  of  the 
geological  survey  of  Canada  in  the  summer  of  1861,  on  the 
Labrador  coast,  along  the  Strait  of  Belleisle ;  where  Olenellus 
(Paradoxides)  Thompsoni  and  0.  Vermontana,  were  found  with 
Conocoryphe  (Conocephalus)  in  strata  which  were  by  Billings 


394      CAMBRIAN  AND   SILURIAN  IN   NORTH  AMERICA.      [XV. 

referred  to  the  Potsdam  group.  (See,  for  the  further  history 
of  these  fossils  the  Geology  of  Canada,  pages  866,  955,  and 
Pal.  Fossils  of  Canada,  pages  11,  419.) 

The  interstratification  of  the  dark-colored  fossiliferous  shales 
holding  Olenellus  with  the  Red  sand-rock  of  Vermont,  an- 
nounced by  Mr.  Billings,  was  further  confirmed  by  Sir  William 
Logan  in  his  account  of  the  section  at  Swanton,  Vermont. 
(Geology  of  Canada,  281.)  They  were  there  declared  to  occur 
about  500  feet  from  the  base  of  a  series  of  2,200  feet  of  strata, 
consisting  chiefly  of  red  sandy  dolomites  (the  so-called  sand- 
rock)  containing  ConocepJialus  throughout,  while  the  shaly  beds 
held,  in  addition,  the  two  species  of  Paradoxides  (Olenellus) 
and  some  brachiopods.  These  beds,  like  those  of  Labrador, 
were  referred  by  Logan  and  by  Billings  to  the  Potsdam  group. 
The  conclusions  here  announced  were  of  great  importance  for 
the  history  of  the  Taconic  controversy.  The  trilobites  of  pri- 
mordial type,  from  Georgia,  Vermont,  which  by  Emmons  were 
placed  in  the  Taconic  system,  lying  unconformably  beneath  a 
series  of  rocks  belonging  to  the  lower  part  of  the  New  York 
system,  were  now  declared  to  belong  to  the  Red  sand-rock 
group,  a  member  of  this  overlying  system.  Much  has  been 
said  of  these  fossils,  as  if  they  furnished  in  some  way  a  vindi- 
cation of  the  views  of  Emmons,  and  of  the  Taconic  system ;  a 
conclusion  which  can  only  be  deduced  from  a  misconception 
of  the  facts  in  the  case.  Emmons  had,  previous  to  1860, 
on  lithological  and  stratigraphical  evidence  alone,  called  the 
Georgia  slates  Taconic,  and  placed  them  unconformably  be- 
neath the  Red  sand-rock.  If  now  both  he  and  Billings  were 
right  in  referring  the  Red  sand-rock  to  the  Calciferous  and 
Potsdam  formations,  and  if  the  stratigraphical  determinations 
of  Messrs.  Perry  and  G.  M.  Hall,  confirmed  by  those  of  Logan, 
were  correct,  namely,  that  the  trilobites  in  question  occur  not 
in  a  system  of  strata  lying  unconformably  beneath  the  Red 
sand-rock,  but  in  beds  intercalated  with  the  sand-rock  itself, 
it  is  clear  that  these  trilobites  must  belong  not  to  the  Taconic, 
but  to  the  New  York,  system.  We  shall  return  to  the  ques- 
tion of  the  age  of  these  rocks. 


XV.]      CAMBRIAN   AND   SILURIAN  IN  NORTH  AMERICA.      395 

We  have  seen  that  Professor  James  Hall,  in  1847,  and  again 
in  1859,  referred  trilobites  regarded  by  him  as  species  of  Olenus 
to  the  Hudson-River  group,  or,  in  other  words,  to  the  summit 
of  the  second  palaeozoic  fauna,  while  it  is  now  well  known  that 
they  are  characteristic  of  the  first  fauna.  In  this  reference,  in 
1847,  Professor  Hall  was  justified  by  the  singular  errors  which 
we  have  already  pointed  out  in  the  works  of  Hisinger  on  the 
geology  of  Scandinavia.  (Ante,  page  366.)  In  his  Anteck- 
niugar,  in  1828,  while  the  colored  map  and  accompanying  sec- 
tions show  the  alum-slates  with  Paradoxides  to  lie  beneath, 
and  the  clay-slates  with  graptolites,  above  the  orthoceratite- 
limestone,  the  accompanying  colored  legend,  designed  to  ex- 
plain the  map  and  sections,  gives  these  two  slates  with  the 
numbers  3  and  4,  as  if  they  were  contiguous  and  beneath  the 
limestone,  which  is  numbered  5.  The  student  who,  in  his 
perplexity,  turned  from  this  to  the  later  work  of  Hisinger,  his 
LethaBa  Suecica,  found  the  two  groups  of  slates,  as  before, 
placed  in  juxtaposition,  but  assigned,  together,  to  a  position 
above  the  orthoceratite-limestone.  Thus,  in  either  case,  he 
would  be  led  to  the  conclusion  that  in  Scandinavia  the  alum- 
slates  with  Olenus,  Paradoxides,  and  Conocephalus  (Conoco- 
ryphe)  were  closely  associated  with  the  graptolitic  shales ;  and, 
upon  the  authority  of  the  later  work,  that  the  position  of  both 
of  these  was  there  above  the  orthoceratite-limestones,  and  at 
the  summit  of  the  second  fauna.  The  graptolitic  shales  of 
Scandinavia  were  already  identified  with  those  of  the  Utica 
and  Hudson-River  formations  of  the  New  York  system.  The 
Red  sand-rock  of  Vermont, 'containing  Conocephalus,  had  been, 
both  by  Emmons  and  Adams,  alike  on  lithological  and  strati- 
graphical  grounds,  referred  to  the  still  higher  Medina  sand- 
stone ;  a  view  which,  as  we  have  seen,  was  still  maintained 
and  strongly  defended  by  Adams.  This  was  in  1847,  and 
Angelin's  classification  of  the  transition  rocks  of  Scandinavia, 
fixing  the  position  of  the  various  trilobitic  zones,  did  not  ap- 
pear until  1854. 

Professor  James  Hall  had  therefore  at  this  time  the  strongest 
reasons  for  assigning  the  rocks  containing  Olenus  to  the  sum- 


396      CAMBRIAN  AND   SILUKIAN  IN  NORTH   AMERICA.       [XV. 

mit  of  the  second  fauna.  Before  we  can  understand  his  reasons 
for  maintaining  a  similar  view  in  1859,  we  must  notice  the 
history  of  geological  investigation  in  eastern  Canada.  So  early 
as  1827,  Dr.  Bigsby,  to  whom  North  American  geology  owes 
so  much,  had  given  us  (Proc.  Geol.  Soc.,  I.  37)  a  careful  de- 
scription of  the  geology  of  Quebec  and  its  vicinity.  He  there 
found  resting  directly  upon  the  ancient  gneiss  a  nearly  hori- 
zontal dark-colored  conchiferous  limestone,  having  sometimes 
at  its  base  a  calcareous  conglomerate,  and  well  displayed  on 
the  north  shore  of  the  St.  Lawrence  at  Montmorenci  and  Beau- 
port.  He  distinguished,  moreover,  a  third  group  of  rocks, 
described  by  him  as  a  "slaty  series  composed  of  shale  and 
graywacke,  occasionally  passing  into  a  brown  limestone,  and 
alternating  with  a  calcareous  conglomerate  in  beds,  some  of 
them  charged  with  fossils  ....  derived  from  the  conchifer- 
ous limestone."  (This  fossiliferous  conglomerate  contained 
also  fragments  of  clay-slate.)  From  all  these  circumstances 
Bigsby  concluded  that  the  flat  conchiferous  limestones  were 
older  than  the  highly  inclined  graywacke  series ;  which  latter 
was  described  as  forming  the  ridge  on  which  Quebec  stands,  the 
north  shore  to  Cape  Rouge,  the  island  of  Orleans,  and  the 
southern  or  Point-Levis  shore  of  the  St.  Lawrence ;  where, 
besides  trilobites  and  the  fossils  in  the  conglomerates,  he  no- 
ticed what  he  called  vegetable  impressions,  supposed  to  be 
fucoids.  These  were  the  graptolites  which,  nearly  thirty  years 
later,  were  studied,  described,  and  figured  for  the  geological 
survey  of  Canada  by  Professor  James  Hall,  who  has  shown 
that  two  of  the  species  from  this  locality  were  described  and 
figured  under  the  name  of  fucoids  by  Ad.  Brongniart,  in  1828. 
(Geol.  Sur.  Canada,  Decade  II.  page  60.)  Bigsby,  in  1827, 
conceived  that  the  limestones  of  the  north  shore  might  belong 
to  the  carboniferous  period,  and  noted  the  existence  of  what 
were  called  small  seams  of  coal  in  the  graywacke  series  of  the 
south  shore.  This  substance  which  I  have  since  described  is, 
however,  entirely  distinct  from  coal,  and  occurs  in  fissures,  some- 
times in  the  interstices  of  crystalline  quartz.  It  is  an  insolu- 
ble hydrocarbonaceous  body,  brilliant,  very  fragile,  giving  a 


XV.]       CAMBRIAN  AND   SILURIAN  IN   NORTH  AMERICA.      397 

black  powder,  and  results  apparently  from  the  alteration  of 
a  once  liquid  bitumen.  (American  Journal  of  Science  (2), 
XXXV.  163.) 

In  1842  the  geological  survey  of  Canada  was  begun  by  Sir 
William  Logan,  who  in  a  Preliminary  Report  to  the  govern- 
ment, dated  in  that  year  but  printed  in  1845,  says  (page  19)  : 
"  Of  the  relative  age  of  the  contorted  rocks  of  Point  Levis, 
opposite  Quebec,  I  have  not  any  good  evidence,  though  I  am 
inclined  to  the  opinion  that  they  come  out  from  below  the  flat 
limestones  of  the  St.  Lawrence."  He  however  subsequently 
adds,  in  a  foot-note,  "  The  accumulation  of  evidence  points  to 
the  conclusion  that  the  Point  Levis  rocks  are  superior  to  the 
St.  Lawrence  limestones."  In  1845,  Captain,  now  Admiral 
Bayfield  maintained  the  same  view,  fortifying  himself  by  the 
early  observations  of  Bigsby,  and  expressing  the  opinion  that 
the  flat  limestones  of  Montmorenci  and  Beauport  passed  be- 
neath the  graywacke  series.  These  limestones,  from  their 
fossils,  were  declared  to  be  low  down  in  the  Silurian,  and 
identical  with  those  which  had  been  observed  at  intervals 
along  the  north  shore  of  the  St.  Lawrence  to  Montreal  (Geol. 
Journal,  I.  455),  the  fossiliferous  limestones  of  which  were 
then  well  known  to  belong  to  the  Trenton  group  of  the  New 
York  system.  The  graywacke  series  of  Quebec,  which  was 
still  supposed  by  Bayfield  to  hold  in  its  conglomerates  fossils 
from  these  limestones,  was  therefore  naturally  regarded  as 
belonging  to  the  still  higher  members  of  that  system ;  and,  as 
we  have  seen,  the  green  sandstone  near  Quebec,  a  member  of 
that  series,  had  already,  in  1842,  been  regarded  by  Emmons  as 
the  representative  of  the  Oneida  or  Shawangunk  conglomerate, 
at  the  summit  of  the  Hudson  River  group  of  New  York. 

It  is  to  be  noticed  that  immediately  to  the  northeast  of 
Quebec,  rocks  undoubtedly  of  the  age  of  the  Utica  and  Hud- 
son River  divisions  overlie  conformably  the  Trenton  limestone, 
on  the  left  bank  of  the  St.  Lawrence ;  while  a  few  miles  to 
the  southwest,  strata  of  the  same  age,  and  occupying  a  similar 
stratigraphical  position,  appear  on  both  sides  of  the  St.  Law- 
rence, and  are  traced  continuously  from  this  vicinity  to  the 


398      CAMBRIAN  AND  SILURIAN  IN  NORTH  AMERICA.      [XV. 

valley  of  Lake  Champlain.  These,  moreover,  offer  such  litho- 
logical  resemblances  to  what  was  called  the  gray  wacke  series  of 
Quebec  and  Point  Levis  (which  extends  thence  some  hundreds 
of  miles  northeastward  along  the  right  bank  of  the  St.  Law- 
rence), that  the  two  series  were  readily  confounded,  and  the 
whole  of  the  belt  of  rocks  along  the  southeast  side  of  the 
St.  Lawrence,  from  the  valley  of  Lake  Champlain  to  Gaspe, 
was  naturally  regarded  as  younger  than  the  limestones  -  of  the 
Trenton  group.  It  was  in  1847  that  Sir  William  Logan  com- 
menced his  examination  of  the  rocks  of  this  region,  and  in  his 
Report  for  the  next  year  (1 848,  page  58)  we  find  him  speaking 
of  the  continuous  outcrop  "of  recognized  rocks  of  the  Hudson 
Eiver  group  from  Lake  Champlain  along  the  south  bank  of  the 
St.  Lawrence  to  Cape  Rosier."  In  his  Report  for  1850,  these 
rocks  were  further  noticed  as  extending  from  Point  Levis 
southwest  to  the  Richelieu,  and  northeast  to  Gaspe  (pages  19, 
32).  They  were  described  as  consisting,  in  ascending  sequence 
from  the  Trenton  limestone  and  the  Utica  slate,  of  clay-slates  and 
limestones,  with  graptolites  and  other  fossils,  followed  by  con- 
glomerate-beds supposed  to  contain  Trenton  fossils,  red  and 
green  shales  and  green  sandstones ;  the  details  of  the  section 
being  derived  from  the  neighborhood  of  Quebec  and  Point 
Levis,  and  from  the  rocks  first  described  by  Bigsby.  As  fur- 
ther evidence  with  regard  to  the  supposed  horizon  of  these 
rocks,  to  which  he  subsequently  (in  1860)  gave  the  name  of 
the  Quebec  group,  we  may  cite  a  letter  of  Sir  William  Logan, 
dated  November,  1861  (Amer.  Jour.  Sci.  (2),  XXXIII.  106), 
in  which  he  says  :  "In  1848  and  1849,  founding  myself  upon 
the  apparent  superposition  in  eastern  Canada  of  what  we  now 
call  the  Quebec  group,  I  enunciated  the  opinion  that  the  whole 
series  belonged  to  the  Hudson  River  group  and  its  immediately 
succeeding  formation ;  a  Leptcena  very  like  L.  sericea,  and  an 
Orthis  very  like  0.  testudinaria,  and  taken  by  me  to  be  these 
species,  being  then  the  only  fossils  found  in  the  Canadian  rocks 
in  question.  This  view  supported  Professor  Hall  in  placing, 
as  he  had  already  done,  the  Olenus  rocks  of  New  York  in  the 
Hudson  River  group,  in  accordance  with  Hisinger's  list  of 


XV.]      CAMBRIAN  AND   SILURIAN  IN  NORTH  AMERICA.      399 

Swedish  rocks  as  given  in  the  Lethsea  Suecica  in  1837,  and  not 
as  he  had  previously  given  it."  (Ante,  pages  366  and  395.) 

The  concurrent  evidence  deduced  from  stratigraphy,  from 
geographical  distribution,  from  lithological  and  from  paleonto- 
logical  characters,  thus  led  Logan,  from  the  first,  to  adopt  the 
views  already  expressed  by  Bigsby,  Emmons,  and  Baytield, 
and  to  assign  the  whole  of  the  palaeozoic  rocks  of  the  southeast 
shore  of  the  St.  Lawrence  below  Montreal  to  a  position  in  the 
New  York  system  above  the  Trenton  limestone.  While  thus, 
as  he  says,  founding  his  opinion  on  the  stratigraphical  evidence 
obtained  in  eastern  Canada,  Logan  was  also  influenced  by  the 
consideration  that  the  rocks  in  question  were  continuous  with 
those  in  western  Vermont.  Part  of  the  rocks  of  this  region 
had,  as  we  have  seen,  originally  been  placed  by  Emmons  at 
this  horizon,  while  the  others,  referred  by  him  to  his  Taconic 
system,  were  maintained  by  Henry  D.  Eogers  to  belong  to  the 
Hudson  River  group ;  a  view  which  was  adopted  by  Mather 
and  by  Hall,  and  strongly  defended  by  Adams,  at  that  time 
engaged  in  a  geological  survey  of  Vermont,  with  which,  in 
1846  and  1847,  the  present  writer  was  connected. 

As  regards  the  subsequent  paleontological  discoveries  in 
these  rocks  in  Canada,  it  is  to  be  said  that  the  graptolites 
first  noticed  by  Bigsby  in  1827  were  rediscovered  by  the 
Geological  Survey  at  Point  Levis  in  1854,  and  having  been 
placed  in  the  hands  of  Professor  James  Hall  (who  in  that  year 
first  saw  the  rocks  in  question),  were  partially  described  by  him 
in  a  communication  to  Sir  William  Logan,  dated  April,  1855, 
and  subsequently  at  length  in  1858.  (Report  Geol.  Survey  for 
1857,  page  109,  and  Decade  II.)  They  were  new  forms,  it  is 
true,  but  the  horizon  of  the  graptolites,  both  in  New  York  and 
in  Sweden,  was  the  same  as  that  already  assigned  by  Logan  to 
the  Point  Levis  rocks.  Thus  these  fossils  appeared  to  sustain 
his  view,  and  they  were  accordingly  described  as  belonging  to 
the  Hudson  River  group. 

Up  to  1856  no  other  organic  remains  than  the  graptolites 
and  the  two  species  of  brachiopods  noticed  by  Sir  Wrilliain 
Logan  were  known  to  the  geological  survey  as  belonging  to 


400      CAMBRIAN  AND   SILURIAN   IN   NORTH  AMERICA.       [XV. 

the  Point  Levis  rocks ;  the  trilobites  long  before  observed  by 
Bigsby  not  having  been  rediscovered.  In  1856  the  present 
writer,  while  engaged  in  a  lithological  study  of  the  various 
rocks  of  Point  Levis,  found,  in  the  vicinity  of  the  graptolitic 
shales,  beds  of  what  were  described  by  him  in  1857  (Report 
Geol.  Surv.,  1853-1856,  page  465)  as  "fine  granular  opaque 
limestones,  weathering  bluish-gray,  and  holding  in  abundance 
remains  of  orthoceratites,  trilobites,  and  other  fossils,  which 
are  replaced  by  a  yellow- weathering  dolomite."  In  these, 
which  are  probably  what  Bigsby  had  long  before  described  as 
fossiliferous  conglomerates,  the  dolomitic  matter  is  so  arranged 
as  to  suggest  a  resemblance  to  certain  beds  which  are  really 
conglomerate  in  character,  and  were  at  the  same  time  described 
by  me  as  interstratified  with  the  fossiliferous  limestones,  and 
as  holding  pebbles  of  pure  limestone,  of  dolomite,  and  occa- 
sionally of  quartz  and  of  argillite  ;  the  whole  cemented  by  a 
yellow-weathering  dolomite,  and  occasionally  by  a  nearly  pure 
carbonate  of  lime.  (Ibid.,  466.)  The  included  fragments  of 
argillite  (previously  noticed  by  Bigsby),  which  are  greenish  or 
purplish  in  color,  with  lustrous  surfaces,  are  precisely  similar 
to  those  which  form  great  beds  in  the  crystalline  schists  of  the 
Green  Mountain  series  of  the  Appalachian  hills,  which  extend 
in  a  northeast  and  southwest  course  along  the  southeastern 
border  of  the  rocks  of  the  Quebec  group.  I  conceive  that 
these  argillite  fragments  (like  those  in  the  Potsdam  conglom- 
erate near  Lake  Champlain,  ante,  page  268)  are  derived  from 
the  ancient  schists  of  the  Appalachians. 

This  rediscovery  of  fossiliferous  limestones  at  Point  Levis 
led  to  further  exploration  of  the  locality,  and  in  1857  and  the 
following  years  a  large  collection  of  trilobites,  brachiopods, 
and  other  organic  remains  was  obtained  from  these  limestones 
by  the  geological  survey  of  Canada. 

Mr.  Billings,  who  in  1856  had  been  appointed  paleontolo- 
gist to  the  geological  survey,  at  once  commenced  the  study  of 
these  fossils  from  Point  Levis,  and  at  length  arrived  at  the 
important  conclusion  that  the  organic  remains  there  found 
belonged,  not  to  the  summit  of  the  second  fauna,  but  were  to 


XV.]      CAMBRIAN   AND   SILURIAN  IN  NORTH  AMERICA.      401 

be  assigned  a  position  in  the  first  or  primordial  fauna.  This 
conclusion  he  communicated  to  Mr.  Barrande  in  a  letter  dated 
July  12,  1860  (American  Journal  of  Science  (2),  XXXI.  220), 
and  gave  descriptions  of  many  of  the  organic  forms  in  the 
Canadian  Naturalist  for  the  same  year.  I  have  already  alluded, 
in  describing  the  rocks  of  Point  Levis,  to  the  peculiarities  of 
aspect  which  probably  led  Dr.  Bigsby,  in  1827,  to  confound 
these  fossiliferous  limestones  penetrated  by  dolomite,  with  the 
true  dolomitic  conglomerates  associated  with  them,  and  helped 
him  to  suppose  the  fossils  to  be  derived  from  the  limestones  of 
the  north  shore,  now  known  to  be  younger  rocks.  This  mis- 
take was  a  very  natural  one  at  a  time  when  comparative  pale- 
ontology was  unknown. 

Sir  William  Logan  meanwhile  made  a  careful  stratigraphical 
examination  of  the  rocks  of  Point  Levis,  and,  notwithstanding 
the  peculiarities  of  the  limestones  which  there  contain  the 
primordial  fauna,  declared  himself,  in  December,  1860,  satisfied 
that  "  the  fossils  are  of  the  age  of  the  strata."  In  consequence 
of  the  discovery  of  Mr.  Billings,  Logan  now  proposed  to  sepa- 
rate from  the  Hudson  River  group  the  graywacke  series  of 
Bigsby  and  Bayfield,  and  ascribed  to  it  a  much  greater  an- 
tiquity ;  regarding  it  as  "  a  great  development  of  strata  about 
the  horizon  of  the  Chazy  and  Calciferous,  brought  to  the  sur- 
face by  an  overturn  anticlinal  fold,  with  a  crack  and  a  great 
dislocation  running  along  the  summit,"  by  which  the  rocks  in 
question  were  "brought  to  overlap  the  Hudson  River  forma- 
tion." This  series,  to  which  was  assigned  a  thickness  of  from 
5,000  to  7,000  feet,  he  named  the  Quebec  group,  which  in- 
cluded the  green  sandstones  of  Sillery,  regarded  as  the  summit, 
the  fossiliferous  limestones  and  graptolitic  shales  at  the  base, 
which  afterwards  received  the  name  of  the  Levis  formation, 
and  a  great  intermediate  mass  of  barren  shales  and  sandstones, 
called  the  Lauzon  formation.  The  first  account  of  this  change 
in  the  stratigraphical  views  of  Logan  occurs  in  his  letter  to 
Barrande,  dated  December  31,  1860.  (American  Journal  of 
Science  (2),  XXXI.  216.) 

This  important  distinction  once  established,  it  was  found 


402      CAMBRIAN  AND   SILURIAN   IN  NORTH  AMERICA.       [XV. 

necessary  to  draw  a  line  from  the  St.  Lawrence,  near  Quebec, 
to  the  vicinity  of  Lake  Champlain,  separating  the  true  Hud- 
son Eiver  group,  with  its  overlying  Oneida  or  Medina  rocks, 
on  the  northwest  side,  from  the  so-caDed  Quebec  group,  on  tho 
south  and  east.  This  division  was  by  Logan  ascribed  to  a  con- 
tinuous dislocation,  which  had  disturbed  a  great  conformable 
palseozoic  series,  including  the  whole  of  the  members  of  the 
New  York  system  from  the  base  of  the  Potsdam  to  the  sum- 
mit of  the  Hudson  Eiver  group,  and,  throughout  the  whole 
distance  of  one  hundred  and  sixty  miles,  had  raised  up  the 
lower  formations  in  a  contorted  and  inclined  attitude,  and 
caused  them  to  overlie  in  many  cases  the  higher  formations  of 
the  system.  This  dividing  line  was  by  Logan  traced  north- 
eastward through  the  island  of  Orleans,  the  waters  of  the 
lower  St.  Lawrence,  and  along  the  north  shore  of  Gaspe ;  and 
southwestward  through  Vermont,  across  the  Hudson,  as  for  at 
least  as  Virginia ;  separating,  throughout,  the  rocks  of  the 
Quebec  and  Potsdam  groups,  with  their  primordial  fauna,  from 
those  of  the  Trenton  and  Hudson  Eiver  groups,  with  the  second 
fauna.  This  is  shown  in  the  geological  map  of  eastern  America 
from  Virginia  to  the  St.  Lawrence,  which  appears  in  the  Atlas 
to  the  Geology  of  Canada,  published  in  1865.  In  an  earlier 
geological  map,  published  by  Sir  William  Logan  at  Paris  in 
1855,  before  this  distinction  had  been  drawn,  the  region  in 
question  in  eastern  Canada  is  colored  partly  as  the  Oneida 
formation,  and  partly  as  the  Hudson  Eiver  group ;  while  in 
the  accompanying  text  the  Sillery  sandstone  is  spoken  of  as  the 
equivalent  of  the  Shawangunk  grit  or  Oneida  conglomerate  of 
the  New  York  system.  (Esquisse  Geologique  du  Canada. 
Logan  and  Sterry  Hunt  :  Paris,  1855,  page  51.)  These  rocks 
were  by  Logan  traced  southward  across  the  frontier  of  Canada, 
into  Vermont,  where  they  included  the  Eed  sand-rock  and  its 
associated  slates ;  which  were  thus  by  Logan,  as  well  as  by 
Adams,  looked  upon  as  occupying  a  position  at  the  summit  of 
the  second  fauna.  When,  therefore,  in  1859,  Professor  Hall 
described  the  trilobites  found  in  these  slates  in  Georgia  in  Ver- 
mont, he  referred  them  to  the  genus  Olenus,  whose  primordial 


XV.]       CAMBRIAN  AND   SILURIAN   IN  NORTH  AMERICA,      403 

horizon  in  Europe  was  then  well  determined,  but,  in  deference 
to  the  conclusions  of  Adams  and  of  Logan,  assigned  them  to  a 
position  at  the  summit  of  the  Hudson  River  group ;  Hall  him- 
self never  having  examined  the  region  stratigraphically.  (Amer- 
ican Journal  of  Science  (2),  XXXL  221.)  In  justitication  of 
this  position  he  appended  to  his  description  the  following  note 
(Ibid.,  pages  213,  221)  :  "In  addition  to  the  evidence  hereto- 
fore possessed  regarding  the  position  of  the  slates  containing 
the  trilobites,  I  have  the  testimony  of  Sir  William  Logan  that 
the  shales  of  this  locality  are  in  the  upper  part  of  the  Hudson 
River  group,  or  forming  part  of  a  series  of  strata  which  he  is 
inclined  to  rank  as  a  distinct  group  above  the  Hudson  River 
proper.  It  would  be  quite  superfluous  for  me  to  add  one  word 
in  support  of  the  opinion  of  the  most  able  stratigraphical  geol- 
ogist of  the  American  continent."  Paleontology  and  strati- 
graphy here  came  into  conflict,  and  it  was  not  till  in  1860, 
when  Mr.  Billings,  in  the  face  of  the  evidence  adduced  from 
the  latter,  asserted  the  primordial  age  of  the  Point  Levis  fauna, 
that  Sir  William  Logan  attempted  a  new  explanation  of  the 
stratigraphy  of  the  region ;  declaring  at  the  same  time  that, 
"from  the  physical  structure  alone,  no  person  would  suspect 
the  break  which  must  exist  in  the  neighborhood  of  Quebec ; 
and  without  the  evidence  of  the  fossils  every  one  would  be 
authorized  to  deny  it."  (Ibid.,  page  218.) 

The  typical  Potsdam  sandstone  of  the  New  York  system,  as 
seen  in  the  Ottawa  basin  in  northern  Xew  York  and  the  adja- 
cent parts  of  Canada,  affords  but  a  very  meagre  fauna,  includ- 
ing two  species  of  brachiopods,  one  or  two  gasteropods,  and  a 
single  crustacean,  Conocephalites  (Conocoryphe)  minutus,  found 
at  Keeseville,  Xew  York.  In  1852,  however,  David  Dale 
Owen  found  and  described  an  extensive  fauna  in  Wisconsin, 
from  rocks  which  were  regarded  as  the  equivalent  of  the  Pots- 
dam sandstone  ;  while  the  observations  of  Shumard  in  Texas, 
in  1861,  and  the  latter  ones  of  Hayden  and  Meek  in  the  Black 
Hills,  have  since  still  further  extended  our  knowledge  of  the 
distribution  and  the  organic  remains  of  the  rocks  which  are 
supposed  to  represent,  in  the  west,  the  Potsdam  and  Calcifer- 
ous  formations  of  the  New  York  system. 


404      CAMBRIAN   AND   SILURIAN   IN  NORTH  AMERICA.       [XV. 

As  early  as  1842,  Professor  Hall,  in  a  comparison  of  the 
lower  palaeozoic  rocks  of  New  York  with  those  of  Great  Britain, 
declared  the  Potsdam  to  be  lower  than  the  base  of  the  Upper 
Cambrian  or  Bala  group  of  Sedgwick.  In  1847,  as  we  have 
seen,  he  extended  this  observation  to  the  Calciferous  and 
Chazy,  both  of  which  he  placed  below  this  horizon ;  which 
until  a  year  or  two  previous  had  been  looked  upon  as  the  base 
of  the  palaeozoic  series  in  Great  Britain,  and  was  subsequently 
made  the  lower  limit  of  the  second  fauna  of  Barrande.  Al- 
though from  these  facts  it  was  probable  that  these  lower 
members  of  the  New  York  system  might  correspond  to  the 
primordial  fauna  of  Barrande,  we  still  remained,  in  the  lan- 
guage of  Professor  Hall,  without  "the  means  of  parallelizing 
our  formations  with  those  of  Bohemia,  by  the  fauna  there 
known.  The  nearest  approach  to  the  type  of  the  primordial 
trilobites  was  found  in  the  Potsdam  of  the  northwest,  de- 
scribed by  Dr.  D.  D.  Owen ;  but  none  of  these  had  been 
generically  identified  with  Bohemian  forms,  and  the  prevailing 
opinion,  sanctioned,  as  I  have  understood,  by  Mr.  Barrande, 
was  that  the  primordial  fauna  had  not  been  discovered  in  this 
country  until  the  rediscovery  (in  1856)  of  Paradoxides  Harlani 
at  Braintree,  Massachusetts.  The  fragmentary  fossils  published 
in  Vol.  I.  of  the  Paleontology  of  New  York,  and  similar  forms 
of  the  so-called  Taconic  system,  were  justly  regarded  as  in- 
sufficient to  warrant  any  conclusions."  (Airier.  Jour.  Sci.  (2), 
XXXI.  225.)  Such,  according  to  Prof.  Hall,  was  the  state  of 
the  question  up  to  1860.  The  Conocephalus,  detected  by  him 
from  the  Red  sand-rock  of  Vermont,  in  1847,  and  subse- 
quently recognized  in  Europe  as  an  exclusively  primordial 
type,  seems  to  have  been  forgotten  by  Hall,  and  overlooked  by 
others,  until  it  was  rediscovered  in  the  sand-rock  by  Billings 
in  1861.  He  had  previously,  in  1860,  detected  the  same 
genus  at  Point  Levis,  together  with  Arionellus,  and  other 
purely  primordial  types.  Associated  with  these,  and  with 
many  other  trilobites  belonging  to  the  second  fauna,  were 
found  several  species  of  Dikellocephalus  and  Menocephalus, 
genera  first  made  known  by  Owen  from  the  Potsdam  of  Wis- 


XV.]       CAMBRIAN  AND   SILURIAN  IN  NORTH  AMERICA.      405 

consin.  It  is  by  an  error  that  Messrs.  Harkness  and  Hicks, 
in  a  recent  paper  (Quar.  Geol.  Jour.,  XXVII.  395),  have  as- 
serted that  Owen,  in  1852,  found  there,  together  with  these 
genera,  Conocephalus  and  Arionellus ;  the  history  of  the  first 
discovery  of  these  genera  in  America  being  as  above  given. 
The  limestones  of  Point  Levis  thus  furnished  what  was  hith- 
erto wanting,  —  a  direct  connecting  link  between  the  fauna  of 
the  American  Potsdam  and  the  primordial  zone  of  Bohemia. 

The  history  of  the  Paradoxides  Harlani,  alluded  to  by 
Professor  Hall,  is  as  follows :  in  1834,  Dr.  Jacob  Green  re- 
ceived from  Dr.  Richard  Harlan  the  cast  of  a  large  trilobite 
occurring  in  a  silicious  slate,  which  was  in  the  collection  of 
Francis  Alger  of  Boston,  and,  it  was  supposed,  might  have 
come  from  Trenton  Falls,  £few  York.  Dr.  Green,  who  at  once 
pointed  out  the  fact  that  the  rock  was  wholly  unlike  any  found 
at  this  locality,  declared  the  fossil  to  resemble  greatly  the  Para- 
doxides Tessini,  Brongn.,  —  the  former  Entomolithus  paradoxus 
of  Linnaeus,  from  Westrogothia,  —  and  named  the  species  P. 
Harlani.  (Amer.  Jour.  Sci.  (1),  XXV.  336.)  In  1856,  the 
attention  of  Professor  William  B.  Rogers  was  called  to  a  local- 
ity of  organic  remains  in  Braintree,  on  the  border  of  Quincy, 
Massachusetts,  where,  on  examination,  he  at  once  recognized 
the  Paradoxides  Harlani  in  a  silicious  slate  similar  to  that  of 
the  original  specimen.  This  was  announced  by  him  in  a  com- 
munication to  the  American  Academy  of  Sciences  (Proc.,  VoL 
III.),  as  a  proof  of  the  protozoic  age  of  some  of  the  rocks  of  east- 
ern Massachusetts.  Professor  Rogers  then  called  attention  to 
the  fact  that  this  genus  of  trilobites  is  characteristic  of  the  pri- 
mordial fauna,  and  noticed  that  Barrande  had  already  remarked 
that,  from  the  casts  of  P.  Harlani  in  the  London  School  of 
Mines  and  the  British  Museum  (which  had  been  made  from  the 
original  specimen,  and  distributed  by  Dr.  Green),  this  species 
appeared  to  be  identical  with  P.  spinosus  from  Skrey  in  Bohe- 
mia. 

In  1858,  Salter  found  in  specimens  sent  to  the  Bristol 
Institution  in  England,  by  Mr.  Bennett  of  Newfoundland, 
from  the  promontory  between  St.  Mary's  and  Placentia  Bays, 


406      CAMBRIAN  AND  SILURIAN  IN   NORTH   AMERICA.       [XV. 

in  the  southwestern  part  of  this  island,  a  large  trilobite,  de- 
scribed by  him  as  Paradoxides  Bennettii  (Geol.  Jour.,  XV. 
554),  which  appears,  according  to  Mr.  Billings,  to  be  identical 
with  P.  Harlani.  On  the  same  occasion  Salter  described, 
under  the  name  of  Conocephalites  antiquatus,  a  trilobite  from  a 
collection  of  American  fossils  sent  by  Dr.  Feuchtwanger  of 
New  York  to  the  London  Exhibition  of  1851.  This  was  said 
to  occur  in  a  bowlder  of  brown  sandstone  from  Georgia,  and,  as 
I  have  been  informed  by  Dr.  Feuchtwanger,  was  found  near 
the  town  of  Columbus  in  that  State. 

The  slates  of  St.  John,  New  Brunswick,  and  its  vicinity 
have  recently  yielded  an  abundant  fauna,  examined  by  Pro- 
fessor Hartt,  who  at  once  recognized  its  primordial  character. 
This  conclusion  was  first  announced,  on  the  authority  of  Pro- 
fessor Hartt,  in  a  paper  by  Mr.  G.  F.  Matthew,  in  May,  1865. 
(Geol.  Jour.,  XXI.  426.)  The  rocks  of  this  region  have  afforded 
two  species  of  Paradoxides  and  fourteen  of  Conocoryphe,  to- 
gether with  Agnostus  and  Microdiscus,  all  of  which  have  been 
described  by  Professor  Hartt.  It  may  here  be  noticed  that,  in 
1862,  Professor  Bell  found  in  the  black  shales  of  the  Dart- 
mouth valley,  in  Gaspe,  a  single  specimen  of  a  large  trilobite, 
which,  according  to  Mr.  Billings,  closely  resembles  Paradoxides 
Harlani ,  but  from  its  imperfectly  preserved  condition  cannot 
certainly  be  identified  with  it.  (Geol.  Canada,  page  882.) 

The  geological  examinations  of  Mr.  Alexander  Murray  in 
Newfoundland,  since  1865,  have  shown  that  the  southeastern 
part  of  that  island  contains  a  great  volume  of  Cambrian  rocks, 
estimated  by  him  at  about  6,000  feet  in  all.  No  traces  of  the 
Upper  Cambrian  or  second  fauna  have  been  detected  among 
these,  but  some  portions  contain  the  Paradoxides  already  men- 
tioned, while  others  yield  the  fauna  which  Mr.  Billings  has 
called  Lower  Potsdam.  This  name  was  first  given  in  an  ap- 
pendix (prepared  by  Sir  "William  Logan)  to  Mr.  Murray's  report 
on  Newfoundland  for  1865,  published  in  1866  (page  46  ;  see 
also  Eeport  of  the  Geol.  Survey  of  Canada  for  1866,  page  236). 
The  Lower  Potsdam  was  there  assigned  a  place  above  the  Par- 
adoxides beds  of  the  region,  which  were  called  the  St.  John 


XV.]       CAMBRIAN  AND  SILURIAN   IN   NORTH  AMERICA.      407 

group,  —  the  fossiliferous  strata  of  St.  John,  New  Brunswick, 
being  referred  to  the  same  horizon ;  which  corresponds  to  the 
Menevian  of  Wales,  now  recognized  as  the  summit  of  the  Lower 
Cambrian.  The  succession  of  the  rocks  containing  these  two 
faunas  in  southeastern  Newfoundland  is  not  yet  clear;  the 
Lower  Potsdam  fauna  is  regarded  by  Mr.  Billings  as  identical 
with  that  found  on  the  Strait  of  Bellisle,  at  Bic  (on  the  south 
shore  of  the  river  St.  Lawrence,  below  Quebec),  at  Georgia  in 
Vermont,  and  at  Troy,  New  York ;  but  in  none  of  these  other 
localities  is  it  as  yet  known  to  be  accompanied  by  a  Menevian 
fauna.  The  'trilobites  hitherto  described  from  these  rocks 
belong  to  the  genera  Olenellus,  ConocorypJie,  and  Agnostus ; 
neither  Paradoxides,  which  characterizes  the  Menevian  and  the 
underlying  Harlech  beds  in  Wales,  nor  Olenus,  which  there 
abounds  in  the  rocks  immediately  above  this  horizon,  having 
as  yet  been  described  as  occurring  in  the  Lower  Potsdam  of 
Mr.  Billings.  Future  discoveries  may  perhaps  assign  it  a  place 
below  instead  of  above  the  Menevian  horizon. 

[To  the  above  genera  of  trilobites  occurring  at  Troy,  Mr. 
Ford  has  since  (in  1873)  added  Microdiscus,  which  has  also 
been  found  at  Bic.  This  genus  is  common  to  the  Menevian 
and  the  underlying  Harlech  rocks  in  Wales,  and  is  also,  accord- 
ing to  Emmons,  found  with  graptolites  in  Augusta  County, 
Virginia.  The  strata  which  contain  this  fauna  at  Troy,  as 
described  by  Ford,  are  of  considerable  thickness,  consisting 
of  limestones  with  coarse  sandstones  and  shales,  which,  as  the 
result  of  a  dislocation  or  of  an  overturned  and  eroded  anticlinal, 
are  made  to  overlie,  in  apparent  conformity,  the  beds  of  the 
Utica  or  Hudson  River  group,  the  whole  dipping  eastward. 
(American  Journal  of  Science  (3),  VI.  134.)] 

The  characteristic  Menevian  fauna  in  and  near  St.  John, 
New  Brunswick,  is  found  in  a  band  of  about  one  hundred  and 
fifty  feet,  towards  the  base  of  a  series  of  nearly  vertical  sand- 
stones and  argillites,  underlaid  by  conglomerates,  and  resting 
upon  crystalline  schists,  in  %a  narrow  basin.  The  series,  the 
total  thickness  of  which  is  estimated  by  Messrs.  Matthew  and 
Bailey  at  over  2,000  feet,  contains  Lingula  throughout,  but  has 


408      CAMBRIAN  AND   SILURIAN  IN   NORTH   AMERICA.       [XV. 

yielded  no  remains  of  a  higher  fauna.  The  same  Menevian 
forms  have  been  found  in  small  outlying  areas  of  similar  rocks, 
at  two  or  three  places  north  of  the  St.  John  basin,  but  to  the 
south  of  the  New  Brunswick  coal-field.  To  the  north  of  this 
is  a  broad  belt  of  similar  argillites  and  sandstones,  which  ex- 
tends southwestward  into  the  State  of  Maine.  This  belt  has 
hitherto  yielded  no  organic  remains,  but  is  compared  by  Mr. 
Matthew  to  the  Cambrian  rocks  of  the  St.  John  basin,  and  to 
the  gold-bearing  series  of  Nova  Scotia  (Geol.  Jour.,  XXI. 
427),  which  at  the  same  time  resembles  closely  the  Cambrian 
rocks  of  southeastern  Newfoundland.  This  was  remarked  by 
Dr.  Dawson  in  1860,  when  he  expressed  the  opinion  that  the 
auriferous  rocks  of  Nova  Scotia  were  "  the  continuation  of  the 
older  slate  series  of  Mr.  Jukes  in  Newfoundland,  which  has 
afforded  Paradoxides,"  and  probably  the  equivalent  of  the 
Lingula  flags  of  Wales.  (Supplement  to  Acadian  Geology 
(I860),  page  53;  also  Acad.  Geol.,  2d  ed.,  page  613.)  Asso- 
ciated with  these  gold-bearing  strata,  along  the  Atlantic  coast 
of  Nova  Scotia,  occur  fine-grained  gneisses,  and  mica-schists 
with  andalusite  and  staurolite ;  besides  other  crystalline  schists 
which  are  chloritic  and  dioritic,  and  contain  crystallized  epi- 
dote,  magnetite,  and  menaccanite.  These  two  types  of  crys- 
talline schists  (which,  from  their  stratigraphical  relations,  as 
well  as  from  their  .mineral  condition,  appear  to  be  more  ancient 
than  the  uncrystalline  gold-bearing  strata)  were  in  1860,  as 
now,  regarded  by  me  as  the  equivalents  respectively  of  the 
White  Mountain  and  Green  Moitntain  series  of  the  Appa- 
lachians, as  will  be  seen  by  reference  to  Dr.  Dawson's  work 
just  quoted.  At  that  time,  however,  and  for  many  years  after, 
I  held,  in  common  with  most  American  geologists,  the  opinion 
that  these  two  groups  of  crystalline  schists  were  altered  rocks 
of  a  more  recent  date  than  that  assigned  to  the  auriferous  series 
of  Nova  Scotia  by  Dr.  Dawson,  who  was  much  perplexed  by 
the  difficulty  of  reconciling  this  view  with  his  own.  The  diffi- 
culty is,  however,  at  once  removed  when  we  admit,  as  I  have 
maintained  since  1870,  that  both  of  these  groups  are  pre- 
Cambrian  in  age.  (Anier.  Jour.  Sci.  (2),  L.  83 ;  ante,  pages 
276  and  327.) 


XV.]      CAMBRIAN  AND   SILURIAN  IN   NORTH  AMERICA.      409 

A  notice  by  Mr.  Selwyn  of  some  of  these  crystalline  schists 
in  Nova  Scotia  will  be  found  in  the  Report  of  the  Geological 
Survey  of  Canada  for  1870  (page  271).  He  there  remarks, 
moreover,  the  close  lithological  resemblances  of  the  gold-bear- 
ing strata  to  the  Harlech  grits  and  Lingula  flags  of  North 
Wales,  and  announces  the  discovery  among  these  strata  at  the 
Ovens  gold-mine  in  Lunenburg,  Nova  Scotia,  of  peculiar  or- 
ganic markings  regarded  by  Mr.  Billings  as  identical  with  the 
Eophyton  Limiceanum,  which  is  found  in  the  Regio  Fucoidarum, 
at  the  base  of  the  Cambrian  in  Sweden.  In  the  volume  just 
quoted  (page  269)  will  be  found  some  notes  by  Mr.  Billings 
on  this  fossil,  which  occurs  also  near  St.  John,  New  Brunswick, 
in  strata  supposed  to  underlie  the  Paradoxides  beds.  The 
same  form  is  found  in  Conception  Bay  in  southeastern  New- 
foundland, in  strata  regarded  by  Mr.  Murray  as  higher  than 
those  with  Paradoxides,  and  containing  also  two  new  species 
of  Linyula,  a  Cruziana,  and  several  fucoids.  Still  more  re- 
cently, Eophyton,  accompanied  by  these  same  fucoids,  has  been 
found  by  Mr.  Billings  at  St.  Laurent,  on  the  island  of  Orleans 
near  Quebec,  in  strata  hitherto  referred  by  the  geological  sur- 
vey, on  stratigraphical  grounds,  to  the  Quebec  group.  The 
evidence  adduced  by  Mr.  Billings  tends  to  show  that  this  or- 
ganic form,  whatever  its  nature,  belongs  to  a  very  low  horizon 
in  the  Cambrian. 

As  regards  the  probable  downward  extension  of  these  forms 
of  ancient  life,  I  cannot  refrain  from  citing  the  recent  language 
of  Mr.  Hicks.  (Quar.  Jour.  Geol.  Soc.,  May,  1872,  page  174.) 
After  a  comparative  study  of  the  Lower  Cambrian  fauna,  in- 
cluding that  of  the  Harlech  and  Menevian  rocks  in  Wales,  and 
the  representatives  of  the  latter  in  other  regions,  he  adds  : — 

"  Though  animal  life  was  restricted  to  these  few  types,  yet 
at  this  early  period  the  representatives  of  the  several  orders 
do  not  show  a  very  diminutive  form,  or  a  markedly  imperfect 
state ;  nor  is  there  an  unusual  number  of  blind  species.  The 
earliest  known  brachiopods  are  apparently  as  perfect  as  those 
which  succeed  them ;  and  the  trilobites  are  of  the  largest  and 
best  developed  types.  The  fact  also  that  trilobites  had  attained 
18 


410      CAMBRIAN  AND   SILURIAN  IN  NORTH  AMERICA.      [XV. 

their  maximum  size  at  this  period,  and  that  forms  were  present 
representative  of  almost  every  stage  in  development,  from  the 
little  Agnostus  with  two  rings  to  the  thorax,  and  Microdiscus 
with  four,  to  Erinnys  with  twenty-four,  and  blind  genera  along 
with  those  having  the  largest  eyes,  leads  to  the  conclusion  that 
for  these  several  stages  to  have  taken  place  numerous  previ- 
ous faunas  must  have  had  an  existence,  arid,  moreover,  that 
even  at  this  time  in  the  history  of  our  globe  an  enormous  pe- 
riod had  elapsed  since  life  first  dawned  upon  it." 

The  facts  insisted  upon  by  Hicks  do  not  appear  to  be  in- 
consistent with  the  view  that  at  this  horizon  the  trilobites  had 
already  culminated.  Such  does  not,  however,  appear  to  be 
the  idea  of  Barrande,  who  in  a  recent  learned  essay  upon  the 
trilobitic  fauna  (1871)  has  drawn  from  its  state  of  development 
at  this  early  period  conclusions  strongly  opposed  to  the  theory 
of  derivation. 

The  strata  holding  the  first  fauna  in  southeastern  Newfound- 
land rest  uncoiiformably,  according  to  Mr.  Murray,  upon  what 
he  has  called  the  Intermediate  series  ;  which  is  of  great  thick- 
ness, consists  chiefly  of  crystalline  rocks,  and  is  supposed  by 
him  to  represent  the  Huronian.  He  has,  however,  included  in 
this  intermediate  series  several  thousand  feet  of  sandstones 
and  argillites  which,  near  St.  John's  in  Newfoundland,  are  seen 
to  be  unconformably  overlaid  by  the  fossiliferous  strata  already 
noticed,  and  have  yielded  two  species  of  organic  forms,  lately 
described  by  Mr.  Billings.  One  of  these  is  an  Arenicolites, 
like  the  A.  spiralis  found  in  the  Lower  Cambrian  beds  of  Swe- 
den, and  the  other  a  patella-like  shell,  to  which  he  has  given 
the  name  of  Aspidella  Terranovica.  (Amer.  Jour.  Science  (3), 
III.  223.)  These,  from  their  stratigraphical  position,  have 
been  regarded  as  Huronian ;  but  from  the  lithological  descrip- 
tion of  Mr.  Murray,  the  strata  containing  them  appear  to  be 
unlike  the  great  mass  of  the  Huronian  rocks  of  the  region. 
Their  occurrence  in  these  strata,  in  either  case,  marks  a  down- 
ward extension  of  these  forms  of  palaeozoic  life. 

Mr.  Billings  has  described  from  the  rocks  of  the  first  fauna 
certain  forms  under  the  name  of  Archeocyathus,  one  of  the 


XV.]      CAMBRIAN   AND   SILURIAN   IN   NORTH   AMERICA.      411 

species  of  which,  according  to  Dr.  Dawson,  belonged  to  a  cal- 
careous chambered  foraininiferal  organism  similar  in  its  nature 
to  much  of  the  Stromatopora  of  the  second,  and  the  closely 
related  Coenostroma  of  the  third  fauna.  All  of  these  Dawson 
shows  to  have  strong  affinities  to  Eozoon,  which  is  represented 
by  E.  Canadense  of  the  Laurentian,  and  by  similar  forms  in 
the  newer  crystalline  schists  of  Hastings,  Ontario,  as  well  as 
by  the  E.  Bavaricum  of  the  upper  crystalline  schists  of  Bava- 
ria. The  succession  of  related  foraminiferal  organisms  is  fur- 
ther seen  in  the  Devonian  limestones  of  Michigan,  where  occur 
great  masses  like  Stromatopora,  which  present,  according  to 
Dawson,  a  structure  intermediate  between  the  Eozoon  of  the 
Laurentian  and  the  genera  Parkeria  and  Loftusia  of  the  Cre- 
taceous and  the  Eocene.  These  details  are  taken  from  Dr. 
Dawson's  presidential  address  to  the  Natural  History  Society 
of  Montreal,  in  May,  1872,  where  he  has  announced  some  of 
the  results  of  his  studies,  yet  in  progress,  on  the  earlier 
foraminifera. 

In  1856  the  late  Professor  Emmons  described  (Amer.  Jour. 
Sci.  (2),  XXII.  389),  under  the  name  of  Palceotrochis,  certain 
forms  regarded  by  him  as  organic,  found  in  North  Carolina  in 
a  bed  of  auriferous  quartzite,  among  rocks  referred  to  his 
Taconic  system.  Their  organic  nature  has  also  been  main- 
tained by  Professor  Wurtz,  but  from  my  own  examinations,  I 
agree  with  the  opinion  expressed  by  Professor  Hall,  and  sub- 
sequently supported  by  the  observations  of  Professor  Marsh 
(Ibid.  (2),  XXIII.  278  ;  *XVL.  217),  that  the  forms  to  which 
the  name  of  Palseotrochis  has  been  given  are  nothing  more 
than  silicious  concretions. 

As  regards  the  geological  horizon  of  the  series  of  strata  to 
which  Sir  William  Logan  has  given  the  name  of  the  Quebec 
group,  the  Sillery  and  Lauzon  divisions  have  as  yet  yielded  to 
the  paleontologist  only  two  species  of  Obolella  and  one  of 
Lingula.  Our  comparisons  must  therefore  be  based  upon  the 
fauna  of  the  Levis  limestones  and  graptolitic  shales,  which 
have  already  been  compared  with  the  Middle  Cambrian  of 
Sedgwick  by  the  combined  labors  of  Billings  and  Salter. 


412      CAMBRIAN  AND   SILURIAN  IN  NORTH  AMERICA.       [XV. 

The  former  has,  moreover,  carefully  compared  this  fauna  with 
that  of  the  lower  members  of  the  New  York  system,  in 
which  the  succession  of  organic  life  appears  to  have  been 
very  much  interrupted.  Thus,-  according  to  Mr.  Billings,  of 
the  ninety  species  known  to  exist  in  the  Chazy  limestone 
of  the  Ottawa  basin,  only  twenty-two  species  have  been  ob- 
served to  pass  up  into  the  directly  overlying  Birdseye  and 
Black  River  limestones,  which  form  the  lower  part  of  the 
Trenton  group.  The  break  in  the  succession  between  the 
Chazy  and  the  underlying  Calciferous  sand-rock  in  this  region 
is  still  more  complete ;  since,  according  to  the  same  authority, 
of  forty-four  species  in  the  latter  only  two  pass  up  into  the 
Chazy  limestone.  This  latter  break  appears  to  be  filled,  in  the 
region  to  the  eastward  of  the  Ottawa  basin,  by  the  Levis 
limestone ;  which  has  been  studied  near  Quebec,  and  also 
near  Phillipsburg,  not  far  from  the  outlet  of  Lake  Champlain. 
This  formation  (including  the  accompanying  graptolitic  shales) 
has  yielded,  up  to  the  present  time,  two  hundred  and  nineteen 
species  of  organic  remains  (comprising  seventy-four  of  crus- 
tacea  and  fifty-one  of  graptolitidioe),  none  of  which,  according 
Mr.  Billings,  have  been  found  either  in  the  Potsdam  or  in  the 
Birdseye  and  Black  River  limestone.  Twelve  of  the  species 
of  the  Levis  formation  are,  however,  met  with  in  the  Calcifer- 
ous, and  five  in  the  Chazy  of  the  Ottawa  basin,  and  the  Levis 
is  therefore  regarded  by  Mr.  Billings  as  the  connecting  link 
between  these  two  formations. 

With  regard  to  the  British  equivalents  of  these  rocks,  the 
Levis  limestone,  according  to  Salter,  corresponds  to  the  Tre- 
madoc  beds ;  although  the  species  of  Dikellocephalm  found  in 
the  Levis  rocks  are  by  him  compared  with  those  found  in  the 
Upper  Lingula  flags  or  Dolgelly  beds.  The  graptolitic  strata 
of  Levis,  however,  clearly  represent  the  Arenig  rocks  of  North 
Wales,  the  Skiddaw  group  of  Sedgwick  in  Cumberland,  the 
graptolitic  beds  which  in  Esthonia,  according  to  Schmidt,  are 
found  below  the  orthoceratite-limestones  (Can.  Naturalist  (1), 
VI.  345)  and  those  of  Victoria  in  Australia  (Mem.  Geol.  Sur., 
III.  Part  II.  255,  304).  In  the  Arenig  and  Upper  Tremadoc 


XV.]      CAMBRIAN  AND  SILURIAN   IN  NORTH   AMERICA.      413 

beds  there  appears  to  be,  in  North  Wales,  a  mingling  of  forms 
of  the  first  and  second  faunas,  as  in  the  Levis  and  Chazy 
formations.  The  latter  was  already,  by  Hall,  in  1847,  declared 
to  be  beneath  the  Silurian  horizon  then  recognized  in  Great 
Britain  ;  and  it  is  by  its  fauna  comparatively  isolated  from  the 
strata  both  below  and  above  it.  According  to  a  private  com- 
munication from  Professor  James  Hall,  the  Chazy  limestone  at 
Middleville,  Herkimer  County,  New  York,  to  the  south  of  the 
Adirondacks,  is  wanting,  and  the  basal  beds  of  the  Trenton 
group  (the  Birdseye  limestone)  there  rest  unconformably  upon 
the  Calciferous  sand-rock. 

The  relations  of  the  various  members  of  the  Quebec  group 
to  each  other,  and  of  the  group,  as  a  whole,  to  the  succeeding 
Trenton  and  Hudson  River  groups,  require  further  elucidation. 
If,  as  I  am  disposed  to  believe,  the  southeastward-dipping 
series  of  the  older  strata  near  Quebec  exhibits  the  northwest 
side  of  an  overturned  and  eroded  anticlinal,  in  which  the 
normal  order  of  the  strata  is  inverted,  then  the  Lauzon  and 
Sillery  divisions,  which  there  appear  to  overlie  the  Levis  lime- 
stones and  shales,  are  older  rocks,  occupying  the  position  of 
the  Potsdam  or  of  still  lower  members  of  the  Cambrian.  Sir 
"William  Logan  supposes  the  appearance  of  these  rocks  in  their 
present  attitude  by  the  side  of  the  strata  of  the  Trenton  and 
Hudson  River  groups,  in  the  vicinity  of  Quebec,  to  be  due  to 
a  great  dislocation  and  uplift  subsequent  to  the  deposition 
of  these  higher  rocks ;  but,  as  elsewhere  suggested  (ante,  page 
263),  I  conceive  the  Quebec  group  to  have  been  in  its  present 
upturned  and  disturbed  condition  before  the  deposition  of  the 
Trenton  limestones.  The  supposed  dislocation  and  uplift,  ex- 
tending from  the  Gulf  of  St.  Lawrence  to  Virginia,  is,  accord- 
ing to  this  view,  but  the  outcrop  of  the  rocks  of  the  first  fauna 
from  beneath  the  unconformably  overlying  strata  of  the  second 
fauna.  The  later  movements  along  the  borders  of  the  Appa- 
lachian region  have,  however,  to  some  extent,  affected  these, 
in  their  turn,  and  thus  complicated  the  relations  of  the  two 
series.  This  unconformity,  which  corresponds  to  the  marked 
break  between  the  Levis  and  Trenton  faunas,  is  further  shown 


414      CAMBRIAN   AND   SILURIAN   IN  NORTH  AMERICA.      [XV. 

by  the  stratigraphical  break  and  discordance  in  Herkimer 
County,  New  York  ;  and  by  the  fact  that  beyond  the  limits 
of  the  Ottawa  basin,  on  either  side,  the  limestone  of  the  Tren- 
ton group  rests  directly  on  the  crystalline  rocks ;  the  older 
members  of  the  New  York  system  being  altogether  absent  at 
the  northern  outcrop,  as  well  as  in  the  outliers  of  Trenton 
limestone  seen  at  the  north  of  Lake  Ontario,  and  as  far  to  the 
northeast  as  Lake  St.  John  on  the  Saguenay.  This  distribu- 
tion shows  that  a  considerable  movement,  just  previous  to  the 
Trenton  period,  took  place  both  to  the  west  and  the  east  of 
Adirondack  region,  which  formed  the  southern  boundary  of  the 
Ottawa  basin. 

[Lesley  observes,  "There  are  certainly  evidences  of  some 
obscure  unconformability  between  the  limestones  of  II.  and 
the  slates  of  III.,"  which  immediately  overlie  them- in  the  great 
Appalachian  valley  in  Pennsylvania.  This  horizon  corresponds 
to  the  base  of  the  Trenton  (see,  further,  page  421),  and  the 
evidence  consists  in  the  different  strike  of  the  rocks  of  the  two 
divisions,  that  of  the  overlying  slates  being  always  with  the 
valley,  while  the  limestone-outcrops  often  cross  it  at  various 
angles.  Lesley  appears  to  regard  the  discordance  of  no  great 
importance ;  but  it  deserves  further  study  in  connection  with 
the  evidences  of  a  similar  want  of  conformity  farther  north- 
ward. (Proc.  American  Philosophical  Society,  December,  1864, 
page  469.)' 

[There  are,  as  we  have  seen,  two  breaks  in  the  succession  of 
life  in  the  Ottawa  basin,  the  one  at  the  base  of  the  Trenton 
group,  and  the  other  at  the  base  of  the  Chazy  ;  and  in  this 
connection,  besides  the  fact  of  the  absence  of  the  latter  between 
the  Calciferous  and  Trenton,  observed  by  Hall  in  Herkimer 
County,  New  York,  should  be  noticed  the  remarkable  section 
near  Grenville  on  the  Ottawa,  described  by  Logan  in  the 
Geology  of  Canada.  Here,  at  what  is  regarded  as  the  base  of 
the  Chazy,  a  conglomerate  layer  of  seven  feet,  made  up  of  lime- 
stone pebbles,  rests  upon  beds  of  yellow-weathering  limestone, 
supposed  to  be  magnesian,  and  holding  obscure  fossils  ;  while 
above  it  are  fifty  feet  of  sandstones,  sometimes  conglomerate, 


XV.]       CAMBRIAN  AND  SILURIAN  IN  NORTH  AMERICA.      415 

with  layers  of  shales,  the  whole  representing  a  period  of  dis- 
turbance which  probably  corresponds  to  the  almost  complete 
paleontological  break  between  the  magnesian  limestones  of  the 
Calciferous  and  the  pure  limestones  of  the  Chazy  period.] 

The  Levis  and  Chazy  formations,  as  we  have  seen,  offer  a 
commingling  of  forms  of  the  first  and  second  faunas,  which 
shows  them  to  belong  to  a  period  of  transition  between  the 
two ;  but  it  is  remarkable  that,  so  far  as  yet  observed,  no  rep- 
resentatives of  the  latter  of  these  faunas  are  known  to  the 
east  and  south  of  the  Appalachians,  along  the  Atlantic  coast  j 
the  first  fauna,  whether  in  Massachusetts,  New  Brunswick, 
or  southeastern  Newfoundland,  being  unaccompanied  by  any 
forms  of  the  second.  The  third  fauna,  on  the  contrary,  is 
represented  in  various  localities  both  within  and  to  the  east  of 
the  Appalachian  region,  from  Massachusetts  to  Newfoundland. 
In  parts  of  Gaspe,  and  also  in  Nova  Scotia,  strata  holding 
forms  referred  to  the  Clinton  and  Niagara  divisions  are  met 
with,  as  well  as  other  strata,  of  Lower  Helderberg  age,  asso- 
ciated with  species  of  shells  and  of  plants  which  connect  this 
fauna  with  that  of  the  succeeding  Lower  Devonian  or  Erian 
period.  To  this  Lower  Helderberg  horizon  (corresponding  to 
the  Ludlow  of  England)  appear  to  belong  certain  fossiliferous 
beds  found  along  the  Atlantic  coast  of  Maine  and  of  New 
Brunswick,  in  Nova  Scotia,  and  probably  in  Newfoundland ; 
as  well  as  others  included  in  the  Appalachian  belt  in  Massa- 
chusetts, New  Hampshire,  Vermont,  and  Quebec,  along  the 
Connecticut  valley  and  its  northeastern  prolongation.  The 
fossiliferous  strata  just  noticed,  both  in  the  Connecticut  valley 
and  along  the  Atlantic  coast,  occur  in  small  areas  among  the 
older  crystalline  schists,  often  made  up  of  the  ruins  of  these, 
and  in  highly  inclined  attitudes.  The  same  is  true  in  other 
places  of  the  similarly  situated  strata  of  Cambrian,  Devonian, 
and  Lower  Carboniferous  periods.  These  derived  strata,  of 
different  ages,  have,  from  their  lithological  resemblances  to  the 
parent  rocks,  been  looked  upon  as  examples  of  a  subsequent 
alteration  of  palaeozoic  sediments ;  and  by  a  further  extension 
of  this  notion,  the  pre-Cambrian  crystalline  schists  themselves 


416      CAMBRIAN  AND   SILURIAN  IN   NORTH  AMERICA.       [XV. 

throughout  this  region  have  "been  looked  upon  as  the  result  of 
an  epigenic  change  of  these  various  palaeozoic  strata ;  portions 
of  which,  here  and  there,  were  supposed  to  have  escaped 
conversion,  and  to  have  retained  more  or  less  perfectly  their 
sedimentary  character,  and  their  organic  remains,  elsewhere 
obliterated. 

From  the  absence  of  the  second  fauna  we  may  conclude  that 
the  great  Appalachian  area  was,  at  least  in  New  England  and 
Canada,  above  the  ocean  during  its  period,  and  suffered  a  par- 
tial and  gradual  submergence  in  the  time  of  the  third  fauna. 
This  movement  corresponds  to  the  well-marked  paleontological 
and  stratigraphical  break  between  the  second  and  third  faunas 
in  the  great  continental  basin  to  the  westward,  made  evident 
by  the  appearance  of  the  Oneida  or  Shawangunk  conglomerate 
(apparently  derived  from  the  ruins  of  Lower  Cambrian  rocks) 
which,  in  some  parts,  overlies  the  strata  of  the  Hudson  River 
group.  The  break  is  elsewhere  shown  by  the  absence  of  this 
conglomerate,  and  of  the  succeeding  formations  up  to  the 
Lower  Helderberg  division.  This  latter,  in  the  valley  of  the 
St.  Lawrence,  rests  unconformably  upon  the  strata  of  the  sec- 
ond fauna,  as  it  does  upon  the  older  crystalline  rocks  to  the 
eastward. 

In  Ohio,  according  to  dewberry,  the  base  of  the  rocks  of  the 
third  fauna  (Clinton  and  Medina)  is  represented  by  a  conglom- 
erate which  holds  in  its  pebbles  the  organic  remains  of  the 
underlying  strata  of  the  second  fauna. 

To  the  northeastward  the  island  of  Anticosti  in  the  Gulf  of 
St.  Lawrence  presents  a  succession  of  about  1,400  feet  of  cal- 
careous strata  rich  in  organic  remains,  which,  according  to  Mr. 
Billings,  include  the  species  of  the  Medina,  Clinton,  and  Niag- 
ara formations,  and  were  named  by  him,  in  1857,  the  Anticosti 
group.  They  rest  upon  nearly  1,000  feet  of  almost  horizontal 
strata,  consisting  of  limestones  and  shales  rich  in  organic  re- 
mains, with  many  included  beds  of  limestone-conglomerate. 
This  lower  series  has  by  the  geological  survey  of  Canada  been 
referred  to  the  Hudson  River  group  ;  but,  notwithstanding  the 
large  number  of  forms  of  the  second  fauna  which  it  contains, 


XV.]       CAMBRIAN  AND  SILURIAN   IN   NORTH  AMERICA.      417 

Professor  Shaler  is  disposed  to  look  upon  it  as  younger,  and 
belonging  rather  to  the  succeeding  division.  There  seems  not 
to  have  been  any  marked  paleontological  break  between  the 
second  and  third  faunas  in  this  region ;  and  it  is  worthy  of 
note,  in  this  connection,  that  in  the  outlying  basin  of  palaeozoic 
rocks,  found  at  Lake  St.  John,  to  the  north  of  Anticosti, 
Hali/sites  catenulatus  is  met  with  in  limestones  associated  with 
many  species  of  organic  remains  which  are  characteristic  of 
the  Trenton  and  referred  to  that  group.  (Geology  of  Canada, 
page  165.) 

The  strata  to  which,  in  1857,  Mr.  Billings  gave  the  name 
of  the  Anticosti  group  were  at  the  same  time  designated  by 
him  Middle  Silurian,  in  which  he  subsequently  included  the 
local  subdivision  known  as  the  Guelph  formation,  which  in 
western  Ontario  succeeds  the  Niagara;  the  name  of  Upper 
Silurian  being  thus  reserved  for  the  Lower  Helderberg  division 
and  the  underlying  Onondaga  formation.  (Report  Geol.  Sur. 
Can.,  1857,  page  248  ;  and  Geol.  Can.,  page  20.)  Both  the 
Guelph  and  the  Onondaga  have  been  omitted  from  the  table 
on  page  386  :  the  Guelph,  because  it  was  not  recognized  in  the 
New  York  system,  and  is  by  some  regarded  as  but  a  sub- 
division of  the  Niagara ;  and  the  Onondaga  or  Salina,  for  the 
reason  that  it  is  a  local  deposit  of  magnesian  limestones,  with 
gypsums  and  rock-salt,  destitute  of  organic  remains. 

[The  name  of  Middle  Silurian  was  at  one  time  used  by  the 
geological  survey  of  Great  Britain  to  designate  the  Lower  and 
Upper  Llandovery  rocks,  but  was  not  employed  by  Murchison 
either  in  his  Silurian  System  or  in  the  various  editions  of 
Siluria.  It  is  rejected  by  Lyell  (Students'  Manual  of  Geology, 
page  452),  and  was  referred  to  in  1854  by  Sedgwick  as  a  term 
then  already  abandoned.  (London,  Edinburgh,  and  Dublin 
Philosophical  Magazine  (3),  VIII.  303,  367,  501.)  Ramsay, 
moreover,  though  he  speaks  of  the  rocks  as  an  intermediate 
series,  does  not  make  use  of  the  term  Middle  Silurian.  (Memoirs 
Geological  Survey,  III.  Part  II.  page  2.)  It  is,  however,  once 
more  applied  by  Hicks  in  1873,  and  made  to  embrace,  as 
before,  the  Lower  Llandovery,  included  by  Sedgwick  in  his 
18*  AA 


418      CAMBRIAN  AND   SILURIAN  IN  NORTH  AMERICA.       [XV. 

Upper  Cambrian,  and  the  Upper  Llandovery  or  May  Hill 
sandstone,  the  base  of  his  Silurian.  These  two  contiguous 
though  discordant  formations,  in  fact,  exhibit  a  mingling  of  the 
forms  of  the  second  and  third  faunas.  It  is,  however,  to  be 
noted  that  the  Middle  Silurian  thus  denned  is  by  no  means 
the  equivalent  of  that  of  Mr.  Billings,  who  has  given  the  name, 
not  to  beds  of  passage,  but  to  a  group  well  defined  both  strat- 
igraphically  and  paleontologically  equivalent  to  the  Upper 
Llandovery  and  the  Wenlock  of  England,  or,  in  other  words, 
to  the  fossiliferous  strata  between  the  top  of  the  Hudson  Kiver 
shales  and  the  summit  of  the  Niagara  limestone  (including  the 
Guelph) ;  thus  taking  the  lower  half  of  the  true  Silurian  or  the 
Upper  Silurian  of  Murchison.  That  the  group  of  strata  com- 
prised under  this  latter  name  (the  third  fauna  of  Barrande) 
really  includes  two  very  distinct  faunas,  was  long  since  shown 
by  Hall,  the  break  between  the  two  being  marked  in  New 
York  and  Ontario  by  the  interposition  of  the  non-fossiliferous 
Onondaga  or  Salina  group.  This  series  of  strata,  in  some 
parts  1,000  feet  or  more  in  thickness,  consists  of  red  and  green 
magnesian  marls  with  rock-salt  and  gypsum,  overlaid  by  a  great 
mass  of  magnesian  limestones,  the  whole  having  been  deposited 
in  a  vast  mediterranean  basin  which  extended  from  eastern 
New  York  to  Ohio.  The  Water-lime  beds,  with  their  peculiar 
fossils,  overlying  the  Salina  group,  consist  of  a  magnesian  lime- 
stone lithologically  related  to  the  rocks  below,  and  represent 
the  first  invasion  of  life  into  the  former  dead  sea,  which  was 
followed  by  the  great  deposit  of  non-magnesian  limestones  of 
the  Lower  Helderberg  group.  These,  which  attain  a  great 
thickness  to  the  eastward,  make  up,  with  the  Oriskany  sand- 
stone, a  fourth  palaeozoic  division,  the  equivalent  of  the  Ludlow 
of  England.  In  Gaspe  a  sandstone  formation,  without  any  ap- 
parent unconformity,  connects  the  Oriskany  with  the  great  mass 
of 'Devonian  sandstones  ;  but  in  New  York  and  in  Ontario  evi- 
dences of  an  interruption  in  the  process  of  deposition  are  seen 
in  the  erosion  of  the  Oriskany  previous  to  the  deposition  of  the 
Corniferous  limestone,  which  there  forms  the  base  of  the  De- 
vonian or  the  Erie  division  of  the  New  York  system,  extending 


XV.]      CAMBRIAN  AND   SILURIAN  IN  NORTH  AMERICA.      419 

up  to  the  base  of  the  Carboniferous,  for  which  Dawson  has  sug- 
gested the  more  appropriate  name  of  Erian.  (See  further  the 
author  on  Breaks  in  the  American  Palaeozoic  Series,  and  Hall 
on  the  Relations  of  the  Niagara  and  Lower  Helderberg  For- 
mations, Proc.  American  Association  for  the  Advancement  of 
Science,  1873,  pages  118  and  321.) 

[The  'name  of  Middle  Silurian,  applied  by  Billings  to  the 
group  holding  the  Medina-Niagara  fauna,  should  be  rejected, 
for  the  reason  that  the  group  below  it  has  no  just  title  to  the 
name  of  Lower  Silurian,  but  is  Upper  Cambrian.  The  two 
distinct  faunas  included  in  the  true  Silurian  rocks  might  with 
great  propriety  be  distinguished  as  Lower  and  L'pper  Silurian.] 

The  history  of  the  introduction  of  the  names  of  Silurian 
and  Devonian  into  North  American  geology  now  demands  our 
notice.  Professor  James  Hall,  as  we  have  seen,  while  recog- 
nizing in  the  rocks  of  the  New  York  system  the  representatives 
alike  of  the  British  Cambrian,  Silurian,  and  Devonian,  wisely 
refrained  from  adopting  this  nomenclature,  drawn  from  a  region 
where  wide  diversities  of  opinion  and  controversies  existed  as 
to  the  value  and  significance  of  these  divisions.  Lyell,  how- 
ever, in  the  account  of  his  first  journey  to  the  United  States, 
published  in  1845,  applied  the  terms  Lower  and  L'pper  Silu- 
rian and  Devonian  to  our  palaeozoic  rocks.  Later,  in  1846,  De 
Verneuil,  the  friend  and  the  colleague  of  Murchison  in  his 
Russian  researches,  visited  the  United  States,  and  on  his  return 
to  France,  published,  in  1847  (Bui.  Soc.  Geol.  de  Fr.,  II.  iv, 
12,  646),  an  elaborate  comparison  between  the  European  palae- 
ozoic deposits  and  those  of  North  America,  as  made  known  by 
Hall  and  others.  He  proposed  to  group  the  whole  of  the  rocks 
of  the  New  York  system,  up  to  the  summit  of  the  Hudson 
River  group,  in  the  Lower  Silurian,  and  the  succeeding 
members,  including  the  Lower  Helderberg  and  the  overlying 
Oriskany,  in  the  Upper  Silurian ;  the  remaining  formations  to 
the  base  of  the  Carboniferous  system  being  called  Devonian. 
This  essay  by  De  Verneuil  was  translated  and  abridged  by 
Professor  Hall,  and  published  by  him  in  the  American  Journal 
of  Science  (II.  v,  176,  359  ;  vii,  45,  218),  with  critical  remarks, 


420      CAMBRIAN   AND   SILURIAN   IN   NORTH   AMERICA.       [XV. 

wherein  he  objected  to  the  application  of  this  disputed  nomen- 
clature to  North  American  geology. 

Meanwhile  the  geological  survey  of  Canada  was  in  progress 
under  Logan,  who  in  his  preliminary  Report  in  1842,  and  in 
his  subsequent  ones  for  1844  and  1846,  adopted  the  nomen- 
clature of  the  New  York  system,  without  reference  to  European 
divisions.  Subsequently,  however,  the  usage  of  Lyell  and  De 
Verneuil  was  -adopted  by  Logan,  who  in  his  Report  for  1 848 
(page  57)  spoke  of  the  Clinton  group  as  the  base  of  the  "Upper 
Silurian  series,"  while  in  that  for  1850  (page  34)  he  declared 
the  whole  of  a  great  series  of  fossiliferous  rocks  in  eastern 
Canada,  including  the  Trenton,  Utica,  and  Hudson  River  divis- 
ions, and  the  shales  and  sandstones  of  Quebec  (then  supposed 
to  be  superior  to  these),  to  "  belong  to  the  Lower  Silurian." 
In  the  Report  for  1852  (page  64)  the  Lower  Silurian  was  made 
by  Mr.  Murray  to  include  not  only  the  Utica  and  Trenton,  but 
the  Chazy  limestone,  the  Calciferous  sand-rock  and  the  Potsdam 
sandstone  of  the  New  York  system.  From  this  time  the 
Silurian  nomenclature,  as  applied  by  Lyell  and  De  Yerneuil 
to  our  North  American  rocks,  was  employed  by  the  officers 
of  the  Canadian  geological  survey  (myself  among  the  others), 
and  was  subsequently  adopted  by  Professor  Dana  in  his  Manual 
of  Geology,  published  in  1863. 

The  geological  survey  of  Pennsylvania,  under  the  direction 
of  Professor  Henry  Darwin  Rogers,  was  begun,  like  that  of 
New  York,  in  1836,  and  the  palaeozoic  rocks  of  the  State  were 
at  first  divided,  on  stratigraphical  and  lithological  grounds,  into 
groups,  which  were  designated,  in  ascending  order,  by  Roman 
numerals.  Subsequently,  as  he  informs  us  in  the  Preface  to 
his  final  Report  on  the  Geology  of  Pennsylvania,  Professor  H. 
D.  Rogers,  in  concert  with  his  brother,  Professor  William  B. 
Rogers,  then  directing  the  geological  survey  of  Virginia,  con- 
sidered the  question  of  geological  nomenclature.  Rejecting, 
after  mature  deliberation,  the  classification  and  nomenclature 
both  of  the  British  and  New  York  geological  surveys,  they 
proposed  a  new  one  for  the  whole  palaeozoic  column  to  the  top 
of  the  coal-measures,  founded  on  the  conception  of  a  great 


XV.]      CAMBRIAN  AND   SILURIAN  IN  NORTH  AMERICA.      421 

palaeozoic  day,  the  divisions  of  which  were  designated  by 
names  taken  from  the  sun's  apparent  course  through  the 
heavens.  (Geology  of  Penn.,  I.  vi,  105.)  So  far  as  regards 
the  three  great  groups  which  we  have  recognized  in  the  lower 
palaeozoic  rocks,  the  later  names  of  Rogers,  and  his  earlier 
numerical  designations,  with  their  equivalents  in  the  New 
York  system,  were  as  follows :  — 

Primal  (I.).  This  includes  the  mass  of  2,500  feet  or  more 
of  shales  and  sandstones,  which  in  Pennsylvania  and  Virginia, 
and  farther  southward,  form  the  base  of  the  palaeozoic  series, 
and  rest  upon  crystalline  schists.  The  Primal  division  was 
regarded  by  the  Messrs.  Rogers  as  the  equivalent  both  of  the 
Potsdam  and  the  still  lower  members  of  the  Cambrian. 

Auroral  (II.).  This  division  consists  in  great  part  of  lime- 
stones, often  magnesian,  and  corresponds  to  the  Calciferous, 
Levis,  and  Chazy  formations.  Its  thickness  in  Pennsylvania 
varies  from  2,500  to  5,000  feet,  and,  with  the  preceding  divis- 
ion, it  includes  the  first  fauna  of  Barrande.  The  representa- 
tives of  the  Primal  and  Auroral  divisions  attain  a  great  de- 
velopment in  southwestern  Virginia  and  also  in  eastern  Ten- 
nessee, where  they  have  been  studied  by  Safford. 

Matinal  (III.).  In  this,  which  represents  the  second  fauna, 
were  comprised  the  limestones  of  the  Trenton  group,  together 
with  the  Utica  and  Hudson  River  shales. 

Levant  (IV.).  This  division  corresponds  to  the  Oneida  and 
Shawangunk  conglomerates  and  the  Medina  sandstone. 

Surgent,  Scalent,  and  Pre- Meridional  (V.,  VI.).  In  these 
divisions  were  included  the  representatives  of  the  Clinton, 
Niagara,  and  Lower  Helderberg  groups  of  New  York,  making, 
with  division  IV.,  the  third  fauna  of  Barrande. 

The  parallelism  of  these  divisions  with  the  British  rocks 
was  most  clearly  and  correctly  pointed  out  by  H.  D.  Rogers 
himself,  in  an  explanation  prepared,  as  I  am  informed,  with 
the  collaboration  of  Professor  William  B.  Rogers,  and  pub- 
lished in  1856,  with  a  geological  map  of  North  America  by 
the  former,  in  the  second  edition  of  Keith  Johnson's  Physi- 
cal Atlas.  The  palaeozoic  rocks  of  North  America  are  there 


422      CAMBRIAN   AND  SILURIAN   IN  NORTH  AMERICA.       [XV. 

divided  into  several  groups,  of  which  the  first,  including  the 
Primal,  Auroral,  and  Matinal,  is  declared  to  be  the  near  repre- 
sentative of  "  the  European  palaeozoic  deposits  from  the  first- 
formed  fossiliferous  beds  to  the  close  of  the  Bala  group ;  that 
is  to  say,  the  proximate  representatives  of  the  Cambrian  of 
Sedgwick."  A  second  group  embraces  the  Levant,  S  urgent, 
Scalent,  and  Pre-Meridional.  These  are  said  to  be  "  the  very 
near  representatives  of  the  true  European  Silurian,  regarding 
this  series  as  commencing  with  the  May  Hill  sandstone."  The 
Levant  division  is  further  declared  to  be  the  equivalent  of  the 
sandstone  just  named  ;  while  the  Matinal  is  made  to  corre- 
spond to  the  Llandeilo,  Bala,  or  Upper  Cambrian ;  the  Auroral 
with  the  Festiniog  or  Middle  Cambrian ;  and  the  Primal  with 
the  Lingula  flags,  the  Obolus  sandstone  of  Russia,  and  the  Pri- 
mordial of  Bohemia. 

The  reader  of  the  last  few  pages  of  this  history  will  have 
seen  how  the  Silurian  nomenclature  of  Murchison  and  the 
British  geological  survey  has  been,  through  Lyell,  De  Verneuil, 
and  the  Canadian  survey,  introduced  into  American  geology  in 
opposition  to  the  judgment,  and  against  the  protests  of  James 
Hall  and  the  Messrs.  Rogers,  the  founders  of  American  palaeo- 
zoic geology. 

Three  points  have,  I  think,  been  made  clear  in  the  first  and 
second  parts  of  this  sketch  :  first,  that  the  series  to  which  the 
name  of  Cambrian  was  applied  by  Sedgwick  in  1835  (limited 
by  him  as  to  its  downward  extension,  in  1838)  was  coextensive 
with  the  rocks  characterized  by  the  first  and  second  faunas  ; 
second,  that  the  series  to  which  the  name  of  Silurian  was 
given  by  Murchison  in  1835  included  the  second  and  third 
faunas,  but  that  the  rocks  of  the  second  fauna,  the  Upper 
Cambrian  of  Sedgwick,  were  only  included  in  the  Silurian 
system  of  Murchison  by  a  series  of  errors  and  misconceptions 
in  stratigraphy  on  the  part  of  the  latter,  which  gave  him  no 
right  to  claim  the  rocks  of  the  second  fauna  as  a  lower  mem- 
ber of  his  Silurian  ;  third,  that  there  was  no  ground  whatever 
for  subsequently  annexing  to  the  Silurian  of  Murchison  the 


XV.]      CAMBRIAN  AND   SILURIAN  IN  NORTH  AMERICA.      423 

Lower  and  Middle  Cambrian  divisions  of  Sedgwick,  which 
the  latter  had  separated  from  the  Upper  Cambrian  on  strati- 
graphical  grounds,  and  which  were  subsequently  found  to 
contain  a  distinct  and  more  ancient  fauna. 

The  name  of  Silurian  should  therefore  be  restricted,  as 
maintained  by  Sedgwick  and  by  the  Messrs.  Rogers,  to  the 
rocks  of  the  third  fauna,  the  so-called  Upper  Silurian  of  Mur- 
chison ;  and  the  names  of  Middle  Silurian,  Lower  Silurian, 
and  Primordial  Silurian  banished  from  our  nomenclature. 
The  Cambrian  of  Sedgwick,  however,  includes  the  rocks  both 
of  the  first  and  second  faunas.  To  the  former  of  these,  the 
lower  and  middle  divisions  of  the  Cambrian  (the  Bangor  and 
Festiniog  groups  of  Sedgwick),  Phillips,  Lyell,  Davidson, 
Harkness,  Hicks,  and  other  British  geologists  agree  in  apply- 
ing the  name  of  Cambrian.  The  great  Bala  group  of  Sedg- 
wick, which  constitutes  his  Upper  Cambrian,  is,  however,  as 
distinct  from  the  last  as  it  is  from  the  overlying  Silurian,  and 
deserves  a  not  less  distinctive  name  than  these  two.  Its  origi- 
nal designation  of  Upper  Cambrian,  given  when  the  zoological 
importance  of  Lower  and  Middle  Cambrian  was  as  yet  un- 
known, is  not  sufficiently  characteristic,  and  the  same  is  to 
be  said  of  the  name  of  Lower  Silurian,  wrongly  imposed  upon 
it.  The  importance  of  this  great  Bala  group  in  Britain,  and 
of  its  Xorth  American  equivalent,  the  Matinal  of  Rogers,  — 
including  the  whole  of  the  limestones  of  the  Trenton  group, 
with  the  succeeding  Utica  and  Hudson  River  shales,  —  might 
justify  the  invention  of  a  new  and  special  name.  That  of 
Cambro-Silurian,  at  one  time  proposed  by  Sedgwick  himself, 
and  adopted  by  Phillips  and  by  Jukes,  was  subsequently  with- 
drawn by  him,  when  investigations  made  it  clear  that  this 
group  had  been  wrongly  united  with  the  Silurian  by  Murchi- 
son.  Deference  to  Sedgwick  should  therefore  prevent  us  from 
restoring  this  name,  which,  moreover,  from  its  composition, 
connects  the  group  rather  with  the  Silurian  than  the  Cambrian. 
Neither  of  these  objections  can  be  urged  against  the  similarly 
constructed  term  of  Siluro-Cambrian,  which,  moreover,  has  the 
advantage  that  no  other  new  name  could  possess,  —  of  connect- 


424      CAMBRIAN  AND   SILURIAN  IN   NORTH   AMERICA.       [XV. 

ing  the  group  both  with  the  true  Silurian,  to  which  it  has 
very  generally  been  united,  and  with  the  Cambrian,  of  which, 
from  the  first,  it  has  formed  a  part.  I  therefore  venture  to 
suggest  the  name  of  Siluro- Cambrian,  as  a  convenient  syno- 
nyme  for  the  Upper  Cambrian  of  Sedgwick  (the  Lower  Silu- 
rian of  Murchison),  corresponding  to  the  second  fauna ;  reserv- 
ing, at  the  same  time,  the  name  of  Cambrian  for  the  rocks  of 
the  first  fauna,  —  the  Lower  and  Middle  Cambrian  of  Sedg- 
wick, —  and  restricting,  with  him,  the  name  of  Silurian  to  the 
rocks  of  the  third  fauna,  —  the  Upper  Silurian  of  Murchison.* 
The  late  Professor  Jukes,  it  may  be  here  mentioned,  in  his 
Manual  of  Geology,  published  in  1857,  still  retained  for  the 
Bala  group  the  name  of  Cambro-Silurian  (which  had  been 
withdrawn  by  Sedgwick  in  1854),  and  reserved  the  name  of 
the  "  true  Silurian  period  "  for  the  Upper  Silurian  of  Murchi- 
son. In  his  recent  and  much-improved  edition  of  this  excel- 
lent Manual  (1872),  Professor  Giekie,  the  director  of  the 
geological  survey  of  Scotland,  has  substituted  the  nomencla- 
ture of  Murchison  ;  with  the  important  exception,  however, 
that  he  follows  Hicks  and  Salter  in  separating  the  Menevian 
from  the  Lingula  flags,  and  uniting  it  with  the  underlying 
Harlech  rocks  (as  has  been  done  in  the  table  on  page  386), 
giving  to  the  two  the  name  of  Cambrian  (loc.  cit.,  pages  526  - 
529),  and  thus,  on  good  paleontological  grounds,  extending 
this  name  above  the  horizon  admitted  by  Murchison.  Bar: 
rande,  on  the  contrary,  in  his  recent  essay  on  trilobites  (1871, 
page  250),  makes  the  Silurian  to  include  not  only  the  Lingula 
flags  proper  (Maentwrog,  Festiniog,  and  Dolgelly),  but  the 
Menevian,  and  even  a  great  part  of  the  Harlech  rocks  thern- 

*  Dr.  Dawson,  in  his  address  as  president  of  the  Natural  History  Society 
of  Montreal,  in  May,  1872,  has  taken  the  occasion  of  the  publication  in  the 
Canadian  Naturalist  of  the  first  and  second  parts  of  this  history,  to  review 
the  subject  here  discussed.  Recognizing  the  necessity  of  a  reform  in  the 
nomenclature  of  the  palaeozoic  rocks  in  conformity  with  the  views  of  Sedg- 
wick, he  would  restrict  to  the  rocks  of  the  third  fauna  the  name  of 'Silurian, 
making  it  a  division  equivalent  to  Devonian  ;  and  while  reserving,  with  Lyell, 
Phillips,  and  others,  the  name  of  Cambrian  for  the  first  fauna  only,  agrees 
with  me  in  the  propriety  of  adopting  the  name  of  Siluro- Cambrian  for  the 
second  fauna. 


XV.]      CAMBRIAN  AND   SILURIAN   IN   NORTH  AMERICA.      425 

selves  (the  Cambrian  of  Murchison  and  the  geological  survey), 
for  the  reason  that  the  primordial  fauna  has  now  been  shown 
by  Hicks  to  extend  towards  their  base.  This,  although  con- 
sistent with  Barrande's  previous  views  as  to  the  extension  of 
the  name  Silurian,  is  a  still  greater  violation  of  historic  truth. 
By  thus  making  the  Silurian  system  of  Murchison  to  include 
successively  the  Upper  Cambrian  and  the  Middle  Cambrian 
of  Sedgwick,  and  finally  his  Lower  Cambrian  (the  Cambrian 
system  of  Murchison  himself),  we  seem  to  have  arrived  at  a 
reductio  ad  absurdum  of  the  Silurian  nomenclature ;  and  we 
may  apply  to  Siluria,  as  Sedgwick  has  already  done,  the  apt 
quotation  once  used  by  Conybeare  with  reference  to  the  Gray- 
wacke  of  the  older  geologists,  which  it  replaces  :  "  Est  Jupiter 
quodcunque  vides" 

It  would  be  unjust  to  conclude  this  historical  sketch  of  the 
names  Cambrian  and  Silurian  in  geology,  without  a  passing 
tribute  to  the  venerable  Sedgwick,  who  to-day,  at  the  age  of 
eighty-seven  years,  still  retains  unimpaired  his  great  powers  of 
mind,  and  his  interest  in  the  progress  of  geological  science.* 
The  labors  of  his  successors  in  the  study  of  British  geology, 
up  to  the  present  time,  have  only  served  to  confirm  the  exacti- 
tude of  his  early  stratigraphical  determinations  ;  and  the  last 
results  of  investigations  on  both  continents  unite  in  showing 
that  in  the  Cambrian  series,  as  defined  by  him  more  than  a 
generation  since,  he  laid,  on  a  sure  foundation,  the  bases  of 
paleozoic  geology. 

*  See  the  Preface  to  this  paper  for  a  notice  of  his  death. 


XVI. 

THEORY  OF  CHEMICAL  CHANGES  AND 
EQUIVALENT  VOLUMES. 

(1853.) 

The  following  paper  was  published  under  the  title  of  Considerations  on  the  Theory 
of  Chemical  Changes,  etc.,  in  the  American  Journal  of  Science  for  March,  1853.  It 
soon  after  appeared  in  the  London,  Edinburgh,  and  Dublin  Philosophical  Magazine  (4), 
V.  526,  and  was  translated  into  German  and  appeared  in  the  Chemisches  Centralblatt  of 
Leipsic  in  the  same  year  (page  849).  In  the  papers  which  follow,  on  The  Composition 
and  Equivalent  Volume  of  Mineral  Species,  on  Solution  and  the  Chemical  Process,  on 
The  Objects  and  Method  of  Mineralogy,  as  well  as  in  that  on  The  Theory  of  Types  in 
Chemistry,  I  have  attempted  to  develop  some  of  the  notions  contained  in  this  first 
essay,  which,  I  still  think,  must  form  the  basis  of  a  rational  theory  of  chemistry 
and  a  true  mineralogical  classification. 

IN  the  proposed  inquiry  we  commence  by  distinguishing  be- 
tween the  phenomena  which  belong  to  the  domain  of  physics 
and  those  which  make  up  the  chemical  history  of  matter.  We 
conceive  of  matter  as  influenced  by  two  forces,  one  of  which 
produces  condensation,  attraction,  and  unity,  and  the  other  ex- 
pansion, repulsion,  and  plurality.  Weight,  as  the  result  of 
attraction,  is  a  universal  property  of  matter.  Besides  this,  we 
have  its  various  conditions  of  consistence,  shape,  and  volume, 
with  the  relation  of  the  latter  to  weight,  constituting  specific 
gravity,  and  the  relations  of  heat,  light,  electricity,  and  magnet- 
ism. A  description  of  these  qualities  and  relations  consti- 
tutes the  physical  history  of  matter,  and  the  group  of  characters 
which  serve  to.  distinguish  one  species  from  another  may  be 
designated  the  apparent  or  specific  form  of  a  species,  as  distin- 
guished from  its  essential  form. 

The  forces  above  mentioned  modify  physically  the  specific 
characters  of  matter,  but  they  have  besides  important  relations 


XVI .]    ON  THE  THEORY  OF  CHEMICAL  CHANGES.     427 

to  those  higher  processes  which  give  rise  to  new  species  by  a 
complete  change  in  the  specific  phenomena  of  bodies.  In  the 
capacity  of  such  complete  change  consists  the  chemical  activity 
of  matter. 

It  is  necessary  to  distinguish  between  the  production  of  new 
species  differing  in  physical  characters,  and  that  reproduction 
which  belongs  to  organic  existences.  The  distinction  arises 
from  that  individuation  which  marks  the  results  of  organic  life, 
and  is  eminently  characteristic  of  its  higher  forms.  The  indi- 
viduality not  only  of  the  organism,  but  of  its  several  parts,  is 
more  evident  as  we  ascend  the  scale  of  organic  life,  while  inor- 
ganic bodies  have  a  specific  existence,  but  no  individuality; 
division  does  not  destroy  them.  Crystallization  is  a  commence- 
ment of  individuation,  and  crystals  like  the  tissues  of  plants 
and  animals  must  be  destroyed  before  they  can  become  the 
subjects  of  chemical  change  ;  corpora  non  agunt  nisi  soluta. 

That  mode  of  generation  which  produces  individuals  like  the 
parent  can  present  no  analogy  to  the  phenomena  under  con- 
sideration ;  metagenesis,  or  alternate  generation,  and  metamor- 
phosis are,  however,  to  a  certain  extent,  prefigured  in  the  chem- 
ical changes  of  bodies.  Their  metagenesis  is  effected  in  two 
ways ;  by  condensation  and  union  on  the  one  hand,  and  by  ex- 
pansion and  division  on  the  other.  In  the  first  case,  two  or 
more  bodies  unite,  and  merge  their  specific  characters  in  those 
of  a  new  species.  In  the  second  case,  this  process  is  reversed, 
and  a  body  breaks  up  into  two  or  more  new  species.  Metamor- 
phosis is  in  the  same  manner  of  two  kinds ;  in  metamorphosis  by 
condensation  only  one  species  is  concerned,  and  in  metamor- 
phosis by  expansion  the  result  is  homogeneous,  and  without 
specific  difference. 

The  chemical  history  of  bodies  is  a  record  of  these  changes  ; 
it  is  in  fact  their  genealogy.  The  processes  of  union  and  divis- 
ion embrace  by  far  the  greater  number  of  chemical  changes,  in 
which  metamorphosis  sustains  a  less  important  part.  By  union, 
we  rise  to  indefinitely  higher  species ;  but  in  division  a  limit  is 
met  with  in  the  production  of  species  which  seem  incapable  of 
further  division,  and  these,  being  regarded  as  primary  or  origi- 


428  ON   THE   THEORY   OF   CHEMICAL   CHANGES.  [XVI. 

nal  species,  are  called  chemical  elements.  These  two  processes 
continually  alternate  with  each  other,  and  a  species  produced 
by  the  first  may  yield,  by  division,  species  unlike  its  parents. 
From  this  succession  results  double  decomposition  or  equivalent 
substitution,  which  always  involves  a  union  followed  by  divis- 
ion, although  under  the  ordinary  conditions  the  process  cannot 
be  arrested  at  the  intermediate  stage. 

The  prevalence  of  certain  modes  of  division  in  related  species 
has  given  rise  to  the  different  hypotheses  of  copulates  and  radi- 
cles, which  have  been  made  the  ground  of  systems  of  classifica- 
tion ;  but  these  hypotheses  are  based  on  the  notion  of  dualism, 
which  has  no  other  foundation  than  the  observed  order  of  gen- 
eration, and  they  can  have  no  place  in  a  theory  of  the  science. 
A  body  may  divide  into  two  or  more  new  species,  yet  it  is  evi- 
dent that  these  did  not  pre-exist  in  it,  from  the  fact  that  a 
different  division  may  yield  other  species  whose  pre-existence  is 
incompatible  with  the  last ;  nor  can  the  pre-existence  of  any 
species  but  those  which  we  have  called  primary  be  admitted 
as  possible.  Apart  from  these  considerations,  it  is  to  be  re- 
marked that  our  science  has  to  do  only  with  phenomena,  and 
no  hypothesis  as  to  the  noumenon  or  substance  of  a  species 
under  examination,  based  upon  its  phenomena,  or  those  of  its 
derived  species,  can  ever  be  a  subject  of  science,  for  it  trans- 
cends all  sensible  knowledge. 

For  these  reasons,  it  is  conceived  that  the  notion  of  pre-exist- 
ing elements  or  groups  of  elements  should  find  no  place  in  the 
theory  of  chemistry.  Of  the  relation  which  subsists  between  the 
higher  species  and  those  derived  from  them,  we  can  only  assert 
the  possibility,  and,  under  proper  conditions,  the  certainty  of 
producing  the  one  from  the  other.  Ultimate  chemical  analyses, 
and  the  formulas  deduced  from  them,  serve  to  show  what 
changes  are  possible  in  any  body,  or  to  what  new  species  it 
may  give  rise  by  its  changes. 

Chemical  union  is  interpenetration,  as  Kant  has  taught,  and 
not  juxtaposition,  as  conceived  by  the  atomistic  chemists. 
When  bodies  unite,  their  bulks,  like  their  specific  characters, 
are  lost  in  that  of  the  new  species.  Gases  and  vapors  unite  in 


XVI.]    ON  THE  THEORY  OF  CHEMICAL  CHANGES.     429 

the  proportion  of  one  volume  of  each,  or  in  some  other  simple 
ratio,  and  the  resulting  species  in  the  gaseous  state  occupies 
one  volume,  so  that  the  specific  gravity  of  the  new  species  is 
the  sum  of  those  of  its  factors.  The  converse  of  this  is  true  in 
division,  and  the  united  volumes  of  the  resulting  species  are 
some  simple  multiple  of  that  of  the  parent ;  in  metamorphosis 
a  similar  ratio  is  always  observed. 

Aside  from  the  apparent  exceptions  about  to  be  noticed,  the 
weights  of  equal  volumes  of  gases  and  vapors  are  their  equiva- 
lent weights,  and  the  doctrine  of  chemical  equivalents  is  that 
of  the  equivalency  of  volumes.  According  to  the  atomic 
hypothesis,  these  weights  represent  the -relative  weights  of  the 
atoms,  and  as  equal  volumes  contain  the  same  number  of  atoms, 
these  must  have  similar  volumes,  so  that  we  come  at  last  to  the 
equivalency  of  volumes.  As  chemical  combination  is  not  a 
putting  together  of  molecules,  but  an  interpenetration  of  masses, 
the  application  of  the  atomic  hypothesis  to  explain  the  law  of 
definite  proportions  becomes  wholly  unnecessary.  Chemical 
species  are  homogeneous ;  iota  in  minimis  existit  natura. 
Solution  is  chemical  union,  as  is  indicated  by  the  attendant 
condensation ;  mechanical  admixtures  are  not  accompanied  by 
any  change  of  volume. 

As  two  volumes  of  water-vapor  yield  one  volume  of  oxygen 
and  two  of  hydrogen,  this  has  been  assumed  to  be  the  equiva- 
lent of  water  and  of  hydrogen,  while  oxygen  was  represented 
by  one  volume,  whose  weight  was  8,  that  of  the  volume  of 
hydrogen  being  .5,  so  that  the  weight  of  the  equivalent  of  wa- 
ter was  9.  But  two  volumes  of  hydrogen  unite  without  con- 
densation with  two  of  chlorine,  and  the  resulting  four  volumes 
of  hydrochloric  gas  are  found  to  be  equivalent  to  four  volumes 
of  chlorine,  hydrogen,  or  water-vapor.  Hence  four  volumes  are 
to  be  taken  for  the  equivalent  of  water,  and  it  becomes  H202, 
with  an  equivalent  of  18,  corresponding  to  HC1,  and  to  vola- 
tile species  generally,  whose  equivalents  are  represented  by  four 
volumes  of  vapor ;  from  these,  the  equivalents  of  non-volatile 
species  are  determined  by  comparison. 

Hydrogen,  chlorine,  and  some  other  primary  species  offer 


430  ON  THE  THEORY  OF   CHEMICAL  CHANGES.          [XVI. 

apparent  exceptions  to  the  general  law  of  condensation  and 
equivalency  of  volumes.  When  four  volumes  of  chlorine  unite 
with  four  of  olefiant  gas,  or  of  naphthaline,  the  product  is  con- 
densed into  four  volumes  ;  but  if  the  chlorine  unite  with  the 
same  volume  of  hydrogen  gas,  there  is  no  condensation,  and 
eight  volumes  or  two  equivalents  of  hydrochloric  gas  are  pro- 
duced. This,  however,  is  explained  when  we  find  that  four 
volumes  of  the  chloro-hydrocarbon,  MH,C12,  may  break  up 
into  four  of  a  new  species  MCI,  and  four  of  HC1 ;  a  change 
which  with  the  chloride  of  olefiant  gas  is  effected  by  the  aid  of 
hydrate  of  potash,  and  with  the  chloride  of  naphthaline  takes 
place  spontaneously  at  an  elevated  temperature.  In  the  pro- 
duction of  hydrochloric  gas  from  chlorine  and  hydrogen,  union 
takes  place  followed  by  immediate  expansion  without  specific 
difference,  or  metamorphosis,  while  in  the  production  of  this 
acid  with  the  hydrocarbons  we  observe  the  intermediate  stage. 
If  an  equivalent  of  four  volumes  of  hydrochloric  gas  were  to 
undergo  a  change  like  the  chloride  of  naphthaline,  and  yield  four 
volumes  of  chlorine  and  four  of  hydrogen,  these  species  would 
appear  with  one  half  their  observed  densities ;  hence  we  con- 
clude that  they  are  actually  condensed  to  one  half  their  theo- 
retical volumes,  so  that  four  volumes  of  hydrogen  gas  represent 
not  H,  but  H2.  In  the  same  way,  if  we  conceive  the  quantity 
of  oxygen  produced  from  four  volumes  of  water- vapor  to  repre- 
sent two  equivalents,  it  should  equal  eight  volumes  instead  of 
two,  so  that  it  is  condensed  to  one  fourth,  precisely  as  the  vapor 
of  sulphur  is  condensed  to  one  twelfth  of  its  theoretical  volume. 
As  there  are  no  bodies  which  are  known  to  yield  for  four  vol- 
umes a  less  quantity  than  two  volumes  of  oxygen,  this  may  be 
taken  to  represent  its  equivalent,  and  the  condensation  of  the 
theoretical  volume  is,  like  that  of  hydrogen  and  chlorine,  one 
half.  Water  with  an  equivalent  of  four  volumes  is  then  H20, 
and  its  weight  2  +  16  =  18;  the  same  formula  is  deduced  by 
those  chemists  who  take  two  volumes  for  the  equivalent,  and, 
dividing  the  weight  of  hydrogen,  write  water  H20,  with  an 
equivalent  weight  of  9.  The  condensation  of  these  elements 
is  that  mode  of  metamorphosis  which  constitutes  polymerism, 


XVI.]     ON  THE  THEORY  OF  CHEMICAL  CHANGES.     431 

and  evidently  offers  no  exception  to  the  law  of  equivalent  vol- 
umes. 

The  law  of  Laurent,  that  the  number  of  atoms  of  hydrogen, 
or  of  hydrogen,  chlorine,  nitrogen,  metals,  etc.,  in  any  formula 
corresponding  to  four  volumes  of  vapor,  is  always  a  sum  divisi- 
ble by  two,  clearly  follows  from  the  principles  already  laid 
down,  and  from  the  fact  that  nitrogen  and  the  metals  are 
subject  to  the  same  conditions  as  hydrogen  and  chlorine ;  the 
atoms  have  the  value  which  has  been  assigned  to  H  and  to  Cl 
in  the  formulas  given  above.  The  same  rule  of  divisibility,  as 
Laurent  has  already  shown,  necessarily  holds  in  regard  to  the 
number  of  atoms  of  carbon,  as  well  as  to  the  oxygen  and  sul- 
phur, if  we  take  for  their  equivalent  weights  the  numbers  6,  8, 
and  16  respectively.* 

It  is  to  be  remarked  that  while  the  coefficients  of  H,  Cl,  or 
"N,  in  formulas  where  these  are  associated,  may  be  odd  num- 
bers, those  of  0,  S,  and  C  are  always  even.  This  seems  a 
conclusive  reason  for  doubling  the  equivalents  of  the  latter,  or 
dividing  those  of  hydrogen,  chlorine,  the  metals,  etc.,  according 
as  four  or  two  volumes  are  taken  for  the  equivalent.  [See  p.  176.] 

I  have  elsewhere  pointed  out  that  carbon  and  oxygen  sustain 
such  relations  that  C2H2  may  be  compared  with  02H2  and  with 
02M2,  and,  by  the  substitution  of  nitrogen  for  hydrogen,  with 
C2HX,  prussic  acid,  and  O2X2,  nitrous  oxide  (the  so-called 
compounds  of  nitrous  oxide  with  bases  are  probably  02MX, 
corresponding  to  the  cyanides,  C2MX) ;  while  the  peroxide  of 
hydrogen,  C^Hg,  corresponds  to  04X2,  nitric  oxide,  and  to  0^2, 
cyanogen.  This  relation  has  important  bearings  on  the  history 
of  the  cyanic  series,  and  the  nitric  derivatives  of  the  hydro- 
carbons, t 

The  formulas  of  such  related  species  as  Gerhardt  has  desig* 
nated  chemical  homologues  differ  from  each  other  by  n  C2H2 ; 

*  Laurent,  Recherches  sur  les  combinaisons  azotees,  Ann.  de  Chimie  et  de 
Physique,  November,  1846;  and  American  Journal  of  Science  for  September, 
1848,  p.  174. 

+  See  page  502  of  my  Introduction  to  Organic  Chemistry,  appended  to 
Silliman's  First  Principles  of  Chemistry,  Phila.,  1852  ;  and  the  above  Journal 
for  January,  1853,  p.  151. 


432  ON  THE  THEORY  OF  CHEMICAL   CHANGES.          [XVI. 

if  now  the  relation  between  C  and  0  be  what  we  have  sup- 
posed, it  may  be  expected  that  mineral  species  will  exhibit  the 
same  relations  as  those  of  the  carbon  series,  and  the  principle 
of  homology  be  greatly  extended  in  its  application.  Such  is 
really  the  case,  and  the  history  of  mineral  species  affords  many 
instances  of  isomorphous  silicates  whose  formulas  differ  by 
n02M2,  as  the  tourmalines,  and  the  silicates  of  alumina  and 
magnesia,  while  the  latter,  with  many  zeolites,  exhibit  a  similar 
difference  of  11 02H2.  The  relation  is  in  fact  that  which  exists 
between  neutral  and  surbasic  or  hydrated  salts. 

Laurent  has  asserted  that  salts  of  the  same  base,  with  homol- 
ogous acids  of  the  type  (C2H2)  n  04,  may  be  isomorphous  when 
they  differ  by  02H2,  and  has  pointed  out,  besides,  several  in- 
stances of  what  he  has  called  hemimorphism  in  species  thus 
related,  as  well  as  in  others  differing  by  n  C12.  The  observations 
of  Pasteur  and  Nickles  have  greatly  extended  the  application  of 
these  cases,  which  assume  a  new  importance  in  connection  with 
the  views  here  brought  forward,  and  demand  further  study.* 

But  to  return  :  we  have  seen  that  in  gases  and  vapors  the 
specific  gravity  of  a  species  enables  us  to  fix  its  equivalent, 
which  is  often  a  multiple,  by  some  whole  number,  of  that  cal- 
culated from  the  results  of  ultimate  analysis.  As  the  equiva- 
lents of  non-volatile  species  are  generally  assumed  to  be  those 
quantities  which  sustain  the  simplest  ratio  to  certain  volatile 
ones,  the  real  equivalent  weight  corresponding  to  four  volumes 
of  vapor,  and  consequently  the  theoretical  vapor-density  of  such 
species,  is  liable  to  a  degree  of  the  same  uncertainty  as  those 
deduced  from  ultimate  analysis.  Having,  however,  determined 
the  true  equivalent  of  a  species  from  the  density  of  its  vapor, 
the  inquiry  arises  whether  a  definite  and  constant  relation  may 
not  be  discovered  between  its  vapor-density  and  the  specific 
gravity  of  a  species  in  the  solid  state.  Such  a  relation  being 
established,  and  the  value  of  the  condensation  in  passing  from 
a  gaseous  to  a  solid  state  being  known,  the  equivalents  of 

*  See  Laurent,  Comptes  Rendus  de  1'Acad.,  Tom.  XXVI.  p.  353 ;  and  p.  257 
of  Laurent  and  Gerhardt's  Comptes  Rendus  des  Travaux  de  Chimie  for  1848; 
also  Pasteur,  ibid.,  p.  165  ;  and  Nickles,  ibid,  for  1849,  p.  347. 


XVI.]  ON   EQUIVALENT  VOLUMES.  433 

solids,  like  those  of  vapors,  might  be  determined  from  their 
specific  gravities. 

A  connection  between  equivalent  weight  and  density  is 
evident  in  some  allied  and  isoinorphous  species.  H.  Kopp,  in 
dividing  the  assumed  equivalent  weights  of  such  bodies  by 
their  specific  gravities,  obtained  quantities  which  were  found 
to  be  equal  for  some  of  these  related  species.  These  numbers 
evidently  represent  the  volumes  of  equivalents,  and  in  accord- 
ance with  the  atomic  hypothesis  are  said  to  denote  the  atomic 
volumes.  The  inquiry  of  Kopp  has  been  pursued  by  many 
investigators,  among  whom  are  Schroeder,  Filhol,  Playfair,  and 
Joule,  and,  more  recently,  Dana.  Their  results  show  that  the 
volumes  thus  calculated  for  related  species  of  similar  crystal- 
lization are  generally  identical,  or  sustain  to  each  other  some 
simple  ratio ;  while  Mr.  Dana,  who  has  compared  isomorphous 
species  of  unlike  chemical  constitution,  finds  that  the  calculated 
volumes  are  often  to  each  other  as  the  number  of  equivalents 
of  elements  in  the  formulas  representing  the  species;  thus 
leading  to  the  conclusion  that  the  real  equivalent  weight  is 
either  a  mean  of  that  of  all  the  elements,  or  some  multiple  of 
it.  The  reason  of  this  appears  in  the  fact  that  the  formulas 
of  those  species  in  which  this  relation  is  apparent  generally 
differ  in  the  proportions  of  A1203,  Si03,  MgO,  CaO,  etc.,  and  the 
quantities  obtained  in  dividing  the  equivalent  weights  of  these 
by  the  number  of  elements  are  nearly  equal.  If  we  divide  by 
the  number  of  elements,  the  equivalents  calculated  from  the 
formulas  of  those  species,  it  will  be  seen  that  the  mean  equiva- 
lents vary  with  the  specific  gravity. 

These  investigations  have  been  principally  confined  to  native 
and  artificial  mineral  species,  and  the  equivalents  have  been 
calculated  from  the  formulas  of  Berzelius  and  Rammelsberg, 
which  express  the  simplest  ratios  deducible  from  analysis. 
While  in  conformity  with  the  dualistic  notions,  a  mineral  like 
calcite  or  magnesite  was  regarded  as  a  compound  of  one  equiv- 
alent of  carbonic  acid  and  one  of  lime  or  magnesia,  dolomite 
was  said  to  be  composed  of  one  equivalent  of  each  of  these 
carbonates,  or  of  two  to  three,  as  the  case  might  be,  while  its 
19  BB 


434  ON  EQUIVALENT  VOLUMES.          [XVI. 

density  was  the  mean  of  those  of  its  constituents ;  thus  imply- 
ing that  this  union,  unlike  that  observed  in  gases,  is  juxtapo- 
sition, and  not  interpenetration.  This  system  of  formulas  has 
introduced  such  difficulties  into  the  study  of  the  relations  be- 
fore us,  that  we  find  Mr.  Dana  led  to  the  conclusion  that  "the 
elemental  molecules  are  not  combined  together  or  united  with 
one  another,  in  a  compound,  but  that  under  their  mutual  influ- 
ence each  is  changed  alike,  and  becomes  a  mean  result  of  the 
molecular  forces  in  action."  * 

The  solution  of  these  difficulties  is  very  simple,  and  will 
have  been  inferred  from  the  plan  of  our  inquiry.  It  is  found 
in  the  principle  that  all  species  crystallizing  in  the  same  shape 
have  the  same  equivalent  volume  ;  so  that  their  equivalent 
weights,  as  in  the  case  of  vapors,  are  directly  as  their  densities, 
and  the  equivalents  of  mineral  species  are  as  much  more  ele- 
vated than  those  of  the  carbon  series,  as  their  specific  gravities 
are  higher.  The  rhombohedral  carbonates  must  be  represented 
as  salts  having  from  twelve  to  eighteen  equivalents  of  base, 
replaceable  so  as  to  give  rise  to  a  great  number  of  species,  and 
the  variations  in  the  volume  of  different  carbonates,  as  observed 
by  Kopp,  indicate  the  existence  of  several  homologous  genera, 
which  are  isomorphous. 

The  researches  of  Playfair  and  Joule  have  led  them  to  the 
conclusion  that  in  some  hydrated  salts  which  crystallize  with 
twenty  and  twenty-four  equivalents  of  water,  as  the  carbonate, 
the  triphosphates  and  triarseniates  of  soda,  the  calculated  vol- 
ume coincides  with  that  obtained  by  multiplying  the  volume 
of  ice  (9.8  for  HO  with  an  equivalent  weight  of  9)  by  the 
number  of  equivalents  of  water.  This  result  is  thus  explained ; 
water  in  these  salts  is  in  the  same  state  of  condensation  as  in 
ice,  and  24  HO  thus  condensed  would  occupy  the  volume  of 
24  X  9.8  =  235,  which  is  identical  with  that  of  the  rhombic 
phosphate,  as  20x9. 8  =  198  is  with  that  of  the  carbonate 
of  soda,  C2Na206,20HO.  Alum,  crystallizing  with  24  HO, 
has  a  volume  which  is  greater  than  that  of  phosphate  of  soda, 
and,  according  to  Playfair  and  Joule,  equals  that  of  the  water 
*  American  Journal  of  Science  (2),  Vol.  IX.  p.  245. 


XVI.]  ON   EQUIVALENT  VOLUMES.  435 

in  the  state  of  ice,  with  the  addition  of  the  bases,  the  acid 
being  excluded.*  In  reality,  the  equivalent  volume  of  alum 
is  to  that  of  the  rhombic  phosphate  as  270  :235;  and  24  HO 
crystallizing  in  the  monometric  system  would  have  the  same 
volume  as  alum,  with  a  specific  gravity  of  about  .8,  giving  for 
HO,  11.25  instead  of  9.8. 

What  are  called  the  atomic  volumes  of  crystallized  species 
are  the  comparative  volumes  of  their  crystals.  In  the  rhom- 
bohedral  system,  the  length  of  the  vertical  axis  being  constant, 
the  volume  varies  with  the  length  of  the  lateral  axes,  or,  in 
other  words,  increases  as  the  rhombohedron  becomes  obtuse, 
and  diminishes  as  it  becomes  acute,  the  cube  being  the  limit 
between  the  two.  So  in  the  dimetric  and  trimetric  systems, 
the  length  of  the  vertical  axis  being  unity,  the  volume  dimin- 
ishes as  the  base  of  the  prism,  the  specific  gravity  increasing. 
Moiioclinic  and  triclinic  crystals  may  be  calculated  as  if  deriva- 
tives of  the  trimetric  system,  with  which  they  will  be  found  to 
correspond  in  volume,  t 

It  is  now  necessary  to  determine  what  equivalent  corresponds 
to  a  given  specific  gravity  in  any  crystalline  solid,  or,  in  other 
words,  what  is  the  value  of  the  condensation  which  takes  place 
in  the  change  from  the  gaseous  to  the  solid  state ;  and  here  a 
degree  of  uncertainty  is  met  with,  because  the  equivalent  of  a 
crystallized  species  may  often  be  a  multiple  of  that  deduced 
from  those  chemical  changes  which  only  commence  with  the 
destruction  of  its  crystalline  individuality.  The  simplest  for- 
mula deducible  for  alum  is  KO  S03,  A1203  3  S03,  24 HO,  or 
S4Kal3Oi6,  12H202,  and,  hydrogen  being  unity,  its  equivalent 
is  at  least  474.6,  which,  with  a  specific  gravity  of  1.75,  gives  a 
volume  of  about  270.  Again,  grape-sugar  is  not  less  than 
C24H24024,  if  we  regard  its  combination  with  common  salt  as 
corresponding  to  one  equivalent  of  each  ;  and  the  ferrocyanides 
in  the  same  way  are  represented  by  C12,  etc.  There  are  rea- 
sons for  believing  that  the  equivalents  of  these  species  in  the 

*  Chemical  Society,  Quarterly  Journal,  I.  page  139. 

[t  The  conclusions  in  this  paragraph  may  be  liable  to  correction,  but  I  leave 
them  as  they  were  printed  twenty-one  years  since.l 


436  ON  EQUIVALENT  VOLUMES.  [XVI. 

crystalline  state  correspond  to  some  multiple  of  the  above 
formulas,  a  question  to  be  decided  by  an  examination  of  the 
crystallization  and  specific  gravity  of  species  whose  equivalents 
are  admitted  to  be  higher. 

Favre  and  Silbermann,  from  their  researches  upon  the  heat 
evolved  in  fusion  and  solution,  have  been  led  to  conclude  : 
first,  that  crystallized  salts  are  polymeric  of  these  same  salts  in 
solution,  that  is,  they  are  represented  by  formulas  which  are 
multiples  of  those  deduced  from  analysis  ;  secondly,  that  double 
salts  and  acid  salts  do  not  exist  in  solution,  being  produced 
only  during  crystallization  ;  and,  thirdly,  that  water,  in  crystal- 
lizing, changes  from  HO  to  nHO,  n  being  some  whole  num- 
ber.* These  conclusions  are  seen  to  be  in  accordance  with 
those  deduced  from  a  consideration  of  the  relations  of  density 
and  equivalent  volume.  A  polymerism  is  evident  in  such 
salts  as  sulphate  of  potash  and  cyanide  of  potassium  when  their 
specific  gravities  are  compared  with  those  of  alum  and  the 
ferrocyanide. 

In  the  liquid  state,  the  relation  between  specific  gravity  and 
equivalent  is  not  so  apparent  as  in  solid  species.  The  con- 
densation often  varies  greatly,  even  in  allied  and  homologous 
species,  but  still  exhibits  a  relation  of  volumes.  The  alcohols 
C2H402,  C4H602,  C10H1202,  and  C16H1802  have  very  nearly  the 
same  specific  gravity,  so  that  the  condensation  is  inversely  as 
their  vapor-equivalents.  The  densities  of  wine-alcohol,  acetic 
acid,  and  aldehyde  in  the  liquid  state,  vary  as  their  equivalents, 
so  that  the  calculated  volumes  are  57.5,  55.5,  and  55.  Formic 
and  valeric  acids  show  a  similar  relation  in  density  to  their 
respective  alcohols,  their  calculated  volumes  being  to  these  as 
37.3  :  39,  and  108  :  106.7.  If  to  these  we  add  butyric  acid, 
which  gives  a  volume  of  90,  and  the  density  of  whose  alcohol 
has  not  yet  been  determined,  the  liquid  volumes  for  the  four 
acids,  C2H204,  C4H404,  C8H804,  and  C10H1004,  are  37.3,  55.5, 
90,  and  108.  These  numbers  approximate  to  multiples  of  the 
liquid  volume  of  water  H202,  which  is  18  ;  or  taking  this  as 
unity,  are  very  nearly  as  2,  3,  5,  and  6.  The  interval  between 

*  Comptes  Rendus,  XXII.  823  -  1140,  and  XXIII.  199  -  411. 


XVI.]  ON   EQUIVALENT  VOLUMES.  437 

3  and  5  corresponds  to  propionic  acid  C6H604,  of  whose  specific 
gravity  I  find  no  recorded  observation.  The  density  of  many 
of  these  liquids  is  not  accurately  known,  and  the  results  of 
different  experimenters  are  not  precisely  accordant.  The  spe- 
cific gravity  at  their  boring-points  should  probably  be  chosen 
for  the  purpose  of  comparison,  and  these  approximations  lead 
us  to  expect  that  future  observations  will  establish  a  simple 
relation  between  the  densities  of  liquids  and  their  vapors. 

In  a  succeeding  paper  [XVII.  of  the  present  volume]  it  is 
proposed  to  apply  the  principles  explained  in  the  present  essay 
in  an  examination  of  the  equivalents  of  a  number  of  minerals 
and  other  crystallized  species. 


XVII.    * 

THE  CONSTITUTION  AND  EQUIVALENT 
VOLUME  OF  MINERAL  SPECIES. 

(1853-1863.) 

A  paper  with  the  above  title,  of  which  the  introduction  and  an  analysis  are  given 
below,  appeared  in  the  American  Journal  of  Science  for  September,  1853.  In  the 
Proceedings  of  the  American  Association  for  the  Advancement  of  Science  for  1854, 
the  same  subject  is  continued  in  an  essay  entitled  Illustrations  of  Chemical  Homol- 
ogy.  From  the  author's  abstract  of  this,  which  appeared  in  the  American  Journal 
of  Science  for  September,  1854,  some  extracts  are  here  given,  in  which  will  be  found 
his  views  on  the  constitution  of  the  feldspars,  since  adopted  by  Tschermak,  and  gen- 
erally ascribed  to  him.  Further  illustrations  are  given  by  extracts  from  a  later  paper 
by  the  author  in  the  Compte  Rendu  of  the  French  Academy  of  Sciences  for  June  29, 
1863,  on  saussurite  and  related  minerals.  Some  general  conclusions  in  accordance 
with  the  views  here  expressed  will  be  found  in  Paper  XIX.  of  the  present  volume. 

IN  a  recent  paper  [XVI.  of  the  present  volume]  we  endeav- 
ored to  lay  down  some  principles  which  may  serve  as  the  basis 
of  a  sound  theory  of  chemistry.  Having  explained  the  nature 
of  chemical  changes,  and  the  laws  of  combination,  we  showed 
that  the  volumes  of  the  uniting  species  are  always  merged  in 
that  of  the  new  one,  so  that  the  atomic  theory,  as  applied  by 
Dalton,  which  makes  combination  consist  in  juxtaposition,  is 
untenable.  It  was  further  asserted  that  the  simple  relations 
of  volumes  which  Gay  Lussac  pointed  out  in  the  chemical 
changes  of  gases  apply  to  all  liquid  and  solid  species,  thus 
leading  the  way  to  a  correct  understanding  of  the  equivalent 
volumes  of  the  latter.  While  chemists  have  not  hesitated  to 
assign  high  equivalents  to  bodies  of  the  carbon  series,  they 
have  been  inclined  to  make  the  equivalent  weights  of  denser 
mineral  species  correspond  to  formulas  representing  the  simplest 
possible  ratios.  We  endeavored,  from  a  consideration  of  the 
theory  of  equivalent  volumes,  to  point  out  the  errors  to  which 


XVII.]  CONSTITUTION  AND  VOLUME  OF  MINERAL  SPECIES.  439 

this  method  has  led,  and  to  show  that  we  must  assign  to  most 
mineral  species  much  higher  equivalent  weights  than  have 
hitherto  been  admitted. 

It  was  further  asserted  that  a  relation  similar  to  that  ob- 
served in  the  formulas  of  allied  hydrocarbonaceous  bodies, 
and  designated  as  chemical  homology,  exists  in  the  formulas 
of  mineral  species.  We  have  said  that  these  formulas,  de- 
duced from  the  results  of  analysis,  are  not  to  be  looked  upon 
as  expressing  any  pre-existing  relations  in  the  constitution  of 
the  species,  which  is  not  to  be  regarded  as  a  compound,  but  as 
an  individual,  in  which  the  so-called  chemical  elements  have 
no  actual  existence.  The  arrangements  of  these  in  our  formu- 
las only  serve  to  make  apparent  the  numerical  relations  which 
have  been  found  to  govern  the  transformations  of  the  higher 
species. 

The  formulas  of  homologous  bodies  may  be  represented  as 
series  in  arithmetical  progression.*  The  first  term  may  be  the 
same  as  the  common  difference,  and  the  series  is  then 

6,  26,  3b...nb, 

as  in  the  hydrocarbons  C2H2,  C4H4,  C6H6,  etc.  If  the  first 
term  is  unlike  the  common  difference,  the  series  is 

a,  a  -f-  6,  a  +  26,.. .a  +  n&, 

of  which  the  ammonias,  ^H8,  NH3  +  C2H2,  XH3+  2C2H2,  etc., 
are  examples.  Both  of  these  cases  are  illustrated  in  the  chemi- 
cal history  of  mineral  species. 

In  the  paper  already  referred  to  it  has  been  shown,  from 
the  relations  of  carbon,  sulphur,  and  oxygen  on  the  one  hand, 
and  of  hydrogen  and  the  metals  on  the  other,  that  M2S2, 
MgOfc  and  H202  (M  representing  any  metal)  may  be  compared 
with  H2C.j.  This  view  will  be  applied  in  extending  the  appli- 
cation of  the  principle  of  homology.  The  sesqui-oxides  like 
ferric  oxide,  chromic  oxide,  and  alumina,  will  be  regarded  as 

[*  The  conception  of  progressive  series  in  chemical  compounds  is  generally 
ascribed  to  Gerhardt,  who  made  it  widely  known  in  his  Precis  de  Chimie 
Organique,  but  appears  to  have  been  first  enunciated  by  Dr.  James  Schiel  of 
St.  Louis,  in  1842,  in  Wohler  and  Liebig's  Annalen,  Vol.  XL1II.,  page  107. 
See  farther  the  American  Journal  of  Science  (2),  XXXII.  48,  where  Dr.  Schiel 
has  developed  the  whole  question  of  series  in  a  very  complete  manner.] 


440   CONSTITUTION  AND  VOLUME  OF  MINERAL  SPECIES.  [XVII. 

oxides  of  ferricum,  chromicum,  and  aluminicum,  having  two 
thirds  the  equivalents  ordinarily  assigned  to  these  metals,  and 
represented  by  fe,  cr,  and  al;  so  that  Fe203  becomes  3feO, 
capable  of  replacing  3MgO,  or  3FeO.  In  the  same  way  arsenic 
and  antimony,  in  one  third  their  usual  equivalents,  may  be  rep- 
resented by  as  and  sb  ;  As03  then  becomes  3asO.  Silica,  Si03, 
may  also  be  written  as  3siO,  and  by  this  means  all  these  oxides 
may  be  reduced  to  the  type  M202. 

We  have  further  asserted  that,  for  species  crystallizing  in  the 
same  form,  the  density  varies  directly  as  the  equivalent  weight, 
so  that  the  quantities  obtained  in  dividing  the  one  by  the 
other,  and  known  as  the  atomic  or  equivalent  volumes,  will  be 
equal.  Such  a  relation  is  already  recognized  between  species 
of  the  same  genus,  and  we  now  propose,  having  fixed  an 
equivalent  weight  for  one  species,  to  calculate,  from  their  den- 
sities, those  of  the  species  isomorphous  with  it,  and  to  show 
from  the  formulas  corresponding  to  these  equivalent  weights 
that  the  different  genera  thus  related  are  homologous,  or  ex- 
hibit other  intimate  relations. 

[In  developing  the  subject  in  the  paper  of  which  the  above 
is  the  introduction,  I  began  by  considering  the  volume  of  some 
artificial  salts  the  density  of  which  has  been  carefully  deter- 
mined by  Playfair  and  Joule,  as  given  in  their  elaborate  me- 
moir on  Atomic  Volumes.  The  volume  of  the  four  prismatic 
arseniates  and  phosphates  of  soda,  with  24HO,  was  found  by 
them  to  be  from  233.0  to  235.6;  while  that  of  four  alums, 
with  the  same  number  of  equivalents  of  water,  varied  from 
271.6  to  280.5  ;  the  presumption,  for  obvious  reasons,  being  in 
each  case  in  favor  of  the  greater  density,  and  hence  of  the 
lesser  volumes.  With  the  alums  were  compared  the  equivalent 
volumes  of  the  chlorides  of  sodium  and  potassium,  calculated 
from  their  ordinary  formulas,  and  the  conclusion  reached  that 
the  crystals  of  these  salts  possess  equivalent  weights  which  are 
such  multiples  of  Nad  and  KC1  as  would  give  an  equiva- 
lent volume  equal  to  that  found  for  the  alums,  or  more  proba- 
bly some  multiple  of  the  latter.  With  the  volume  of  the 
arseniates  and  phosphates  of  soda  was  also  compared  that  of 


XVII.]  CONSTITUTION  AND  VOLUME  OF  MINERAL  SPECIES.  441 

ferrocyanide  of  potassium  with  C12  =  230,   and  lactose  with 
Cu  =  234  ;  the  equivalent  weight  of  carbon  being  6. 

[An  attempt  was  then  made  to  fix  the  volume  of  the  pris- 
matic and  rhombohedral  carbon-spars,  which  were  compared  re- 
spectively with  the  isomorphous  species  bournonite  and  the  red 
silver  ores,  proustite  and  pyrargyrite.  The  received  formula 
of  bournonite  being  doubled,  and  that  of  the  rhombohedral  sul- 
phides made  to  correspond  with  it,  we  find  for  the  prismatic 
species  an  equivalent  volume  of  508,  and  for  the  rhombohedral 
ones  546-564.  In  accordance  with  this  the  equivalent  of 
calcite  corresponds  to  CsoCagoOgo  (C  =  6  and  0  =  8),  while 
dolomite,  chalybite,  and  diallogite  become  CggM^D^,  and  cala- 
mine  and  magnesite  C^M^O^.  For  the  prismatic  carbonates, 
aragonite,  like  calcite,  is  CgoMgoOgo,  while  strontianite,  ceru- 
site,  and  bromlite  are  C^M^C^,  and  witherite  is  C^M^O^. 
With  these  were  at  the  same  time  compared  the  homceo- 
morphous  rhombohedral  and  prismatic  nitrates  of  soda  and 
potash,  from  which  it  was  suggested  that  the  above  equiva- 
lents were  to  be  still  further  multiplied.  That  the  volume 
above  fixed  for  these  rhombohedral  species  was,  if  not  the  true 
one,  a  measure  of  it,  was  soon  rendered  more  probable  by  an 
examination  of  the  compound  of  glucose  and  chloride  of 
sodium,  which  was  obtained  in  large  rhombohedral  forms 
isomorphous  with  calcite  and  having  a  density  of  1.563. 
Doubling  the  empirical  formula  of  this  body, 


we  have  for  it  an  equivalent  volume  of  558.5,  while  that  of 
calcite  with  CgoMgoOgo,  and  a  density  of  2.72  =  555.5.  (Amer. 
Jour.  Science  (2),  XIX.  416.) 

[From  Glauber-salt  and  borax  were  deduced,  in  like  manner, 
an  equivalent  volume  of  about  440,  corresponding  nearly  with 
that  of  saccharose  with  C&  =  430,  and  with  these  were  com- 
pared the  silicates  of  the  amphibole  group,  from  which  it  was 
concluded  that  these  silicates  present  among  themselves  rela- 
tions similar  to  those  of  the  homceomorphous  carbon-spars. 
The  attempts  to  deduce  correct  formulas  for  these  and  other 
silicates  at  that  time  were,  however,  vitiated  by  many  incorrect 
19* 


442  CONSTITUTION  AND  VOLUME  OF  MINERAL  SPECIES.  [XVIL 

analyses,  and  rendered  uncertain  by  doubts  as  to  the  equiva- 
lent weight  of  silicon. 

[An  important  point  in  the  question  of  homology  and  homoeo- 
morphism  was  then  referred  to  in  the  following  language  :  — 

"The  similarity  in  crystallization  between  species  whose 
formulas  differ  only  in  the  elements  of  water  has  been  pointed 
out  by  Laurent  in  certain  salts  of  organic  acids,  and  is  seen  in 
several  mineral  species.  The  chabazites,  for  example,  give 
the  formula  3EO,Si03  .  3AL>03,2Si03,  with  15HO  and  18HO, 
while  the  variety  ledererite  affords,  according  to  Hayes  and 
to  Eammelsberg,  but  6 HO.  The  hydrous  iolites  are  also  cases 
in  point,  as  well  as  aspasiolite,  the  serpentines,  and  the  talcs, 
with  their  varying  proportions  of  water.  In  the  formulas  of 
these  species,  water  appears  to  replace  magnesia,  and  Scheerer 
has  shown  that  many  different  species  may  be  referred  to  a 
common  chemical  type,  by  admitting  3HO  to  replace  MgO, 
and  2HO  to  replace  CuO,  etc.  These  cases,  to  which  he  has 
given  the  name  of  polymeric  isomorphism,  are  but  instances 
of  the  partial  substitution  of  water  for  other  bases  in  homolo- 
gous genera  which  differ  by  nMO." 

[In  the  continuation  of  this  subject,  in  1854,  as  above  re- 
ferred to,  the  question  of  homologies  was  further  illustrated 
by  the  neutral  and  the  basic  nitrates  of  lead,  represented  by 
a  common  formula  (Pb202)n  .  ^sr2010.  "  These  salts  vary  in 
solubility  and  in  physical  characters,  but  resemble  each  other 
in  yielding  nitric  acid  and  oxide  of  lead  as  results  of  their  de- 
composition, and  are  completely  analogous  to  the  homologous 
series  of  Gerhardt,  which  differ  by  n(C2H2).  From  the  rela- 
tion between  basic  and  hydrated  salts  the  same  view  is  to  be 
extended  to  the  latter,  and  species  differing  by  n(02H2)  and 
n(02M2)  may  thus  be  homologous.  The  above  formulas  are 
intended  to  involve  no  hypothesis  as  to  the  arrangement  of  the 
elements,  for  in  the  author's  view,  each  species  is  an  individual, 
in  which  the  pre-existence  of  different  species  that  may  be  ob- 
tained by  its  decomposition  cannot  be  asserted.  He  regards 
silicates  like  eudialyte,  sodalite,  and  pyrosmalite  as  oxychlorides, 
(M202)n .  MCI,  and  nosean,  hauyene,  and  lapis-lazuli  as  basic 


XVII.]  CONSTITUTION  AND  VOLUME  OF  MINERAL  SPECIES.   443 

sulphates  (M202)n .  S208,  while  cancrinite,  and  perhaps  some 
scapolites,  are  [may  perhaps  be]  basic  carbonates.  All  other 
silicates  are  reducible  to  the  same  type  as  the  spinels,  n(M202), 

the  formula  of  silica  itself  being  written  siO Boric, 

titanic,  tantalic,  and  niobic  acids  are  reduced  to  the  same  for- 
mula as  silica." 

"  Homoeomorphous  species  have  similar  equivalent  volumes, 
so  that  the  density  in  species  thus  related  enables  us  to  deter- 
mine their  comparative  equivalent  weights,  and  to  fix  their 
positions  in  a  homologous  series.  The  proportion  between  the 
silica  and  the  other  oxides  may  vary  greatly  in  related  species, 
while  the  characters  of  the  genus  or  the  order  are  preserved. 
This  is  illustrated  in  hornblende,  diopside,  and  aluminous 

pyroxenes   like   hudsonite The   triclinic  feldspars,  of 

which  albite  and  anorthite  are  the  representatives,  furnish  an- 
other example."  [These,  it  was  shown,  might  be  reduced  to  a 
common  formula  M^O^,  to  which  petalite  was  also  referred, 
while  orthoclase  was  described  as  belonging  to  a  homologous 
genus,  MgoOeo,  represented  by  (si^al^K^Oa,,  with  the  re- 
mark that  although  this  formula  agrees  with  a  large  num- 
ber of  analyses,  there  are  those  which  appear  to  show  more 
alkali.  Petalite  was  (si51al]0Li3)Ow,  with  a  density  of  2.45 
and  an  equivalent  volume  of  401.5.  The  formulas  then  as- 
signed to  the  two  feldspars  first  named  were,  respectively  :  — ] 

Density.  Eq.  vol. 

Anorthite     .    .     (siM  alJ4  Cag)0M    .    .    2.76    .    .    405.0. 
Albite      .     .     .     (si^  alu  Na4)0M    .    .    2.62    .    .    402.4. 

"  Between  anorthite  and  albite  may  be  placed  vosgite,  labra- 
dorite,  andesine,  and  oligoclase,  whose  composition  and  densi- 
ties are  such  that  they  all  enter  into  the  same  general  formula 
with  them,  and  have  the  same  equivalent  volume.  The  results 
of  their  analysis  are  by  no  means  constant,  and  it  is  probable 
that  many,  if  not  all  of  them  may  be  variable  mixtures  of 
albite  and  anorthite.  Such  crystalline .  mixtures  are  very  com- 
mon ;  thus  in  the  alums,  aluminium,  iron,  and  chromium,  and 
potassium  and  ammonium  may  replace  one  another  in  indefinite 
proportions Heintz  has  shown  by  fractional  precipita- 


444  CONSTITUTION  AND  VOLUME  OF  MINERAL  SPECIES.  [XVII. 

tion  that  there  are  mixtures  of  homologous  fatty  acids  which 
cannot  be  separated  by  crystallization,  and  have  hitherto  been 
regarded  as  distinct  acids.  The  author  insists  that  the  possi- 
bility of  such  mixtures  of  related  species  should  be  constantly 
kept  in  view  in  the  study  of  mineral  chemistry.  The  small 
portions  of  lime  and  potash  in  many  albites,  and  of  soda  in 
anorthite,  petalite,  and  orthoclase,  are  to  be  ascribed  to  mix- 
tures of  other  feldspar-species." 

[The  above  extracts  are  from  the  author's  abstract  of  his 
paper  in  the  American  Journal  of  Science  for  September,  1854. 
There  might  be  found  reason  to-day  for  modifying  the  formu- 
las above  given  for  petalite  and  orthoclase,  but  I  leave  them  as 
they  were  written  twenty  years  since. 

[These  views  of  mine  with  regard  to  the  triclinic  feldspars 
have  since  been  generally  accepted,  but  by  an  oversight  they 
are  attributed  to  Tschermak,  who,  so  far  as  I  am  aware,  first 
announced  them  ten  years  later,  namely,  in  1864  (K.  K.  Aca- 
demic Wissenschaft,  "Wien).  He  there  stated  that  with  the 
exception  of  the  baryta-feldspar,  hyalophane,  and  the  boric 
feldspar,  danburite,  the  feldspars  were  reducible  to  three  spe- 
cies, namely,  adularia  (orthoclase),  albite,  and  anorthite,  hav- 
ing a  common  formula,  which,  adopting  the  equivalent  weights 
used  by  me  above,  becomes  as  follows  for  the  two  triclinic 

species  :  — 

Anorthite        Ca4  a!6  al6  si16  0^ 
Albite  Na2  a!6  si8  siltt  O^ 

This,  which  is  but  my  common  formula  divided  by  two,  is  by 
Tschermak  also  assigned  to  orthoclase.  He,  while  admitting 
that  the  potash-soda  feldspars  are  made  up  of  alternations  of 
orthoclase  and  albite,  as  Gerhard  had  shown  in  the  case  of 
perthite,  further  concludes,  as  I  had  already  done,  "  that  oligo- 
clase,  andesine,  and  labradorite  appear  to  be  members  of  a 
great  series,  with  many  transitional  forms,  and  may  be  regarded 
as  isomorphous  mixtures  of  albite  with  anorthite,  sometimes 
with  small  admixtures  of  orthoclase." 

[My  views  on  the  gradation  into  one  another  of  the  triclinic 
feldspars  are  again  referred  to  in  my  Contributions  to  Lithology, 


XVII.]  CONSTITUTION  AND  VOLUME  OF  MINERAL  SPECIES.   445 

in  the  American  Journal  of  Science  for  March,  1864  (Vol. 
XXV.  page  258),  where  the  family  of  the  feldspathides  is 
made  to  include  the  scapolites  or  wernerites,  and  also  beryl  and 
iolite,  which  have  a  similar  equivalent  volume.  The  former 
is  a  glucinic  feldspathide,  subject,  like  the  feldspars  proper, 
leucite,  and  the  scapolites,  to  kaolinkation ;  while  iolite  is  a 
magnesic  feldspathide,  having  the  oxygen  ratios  5:3:1,  cor- 
responding to  barsowite  and  bytownite,  and  intermediate  be- 
tween labradorite  and  anorthite. 

[The  relations  of  the  feldspathides  to  the  grenatides  (in  which 
are  included  the  garnets,  idocrase,  epidote,  and  zoisite)  fur- 
nish an  important  illustration  of  the  notions  put  forward  in 
the  preceding  pages.  In  the  American  Journal  of  Science  for 
1859  (XXVII.  336)  will  be  found  a  memoir  on  Euphotide  and 
Saussurite,  in  which  I  showed  that  the  saussurite  of  Monte 
Eosa  (the  jade  of  De  Saussure)  does  not  belong,  as  previously 
supposed,  to  the  feldspathides,  but  from  its  chemical  and  physi- 
cal characters  is  to  be  regarded,  as  a  zoisite.  This  substance, 
which  is  very  distinct,  alike  from  the  compact  feldspars  with 
which  it  had  been  confounded,  and  from  the  compact  amphibole 
to  which  also  the  name  of  jade  is  sometimes  given,  has  a  specific 
gravity  of  3.35  and  a  hardness  of  7.0.  It  is  only  attacked 
by  acids  after  intense  ignition  or  fusion,  by  which  it  is  con- 
verted into  a  soft  glass  having  a  specific  gravity  of  2.80.  By 
analysis  it  is  found  to  have  the  composition  of  zoisite  or  of 
meionite,  these  two  species  having  the  same  centesimal  com- 
position. It  has,  however,  the  characters  of  the  former,  and 
differs  widely  from  meionite,  which  is  a  scapolite  having  a 
specific  gravity  of  2.70  and  a  hardness  of  5.5,  and  is  readily 
attacked  and  decomposed  by  acids.  • 

[The  Comptes  Rendus  of  the  French  Academy  of  Science 
for  June  29,  1863,  contains  a  communication  from  me,  which 
is  translated  in  the  American  Journal  of  Science  for  November, 
1863  (page  427).  In  this,  after  giving  in  brief  the  history  of 
euphotide  and  saussurite  and  the  results  of  my  examinations,  I 
said  as  follows,  referring  to  the  memoir  of  1859  :  — 

"In  the  memoir  from  which  the  foregoing  results  are  cited 


446   CONSTITUTION  AND  VOLUME  OF  MINERAL  SPECIES.  [XVII. 

I  have  insisted  upon  the  relation  of  isomerism,  or  rather  of  poly- 
merism,  which  exists  between  meioiiite  and  zoisite,  and  have 
remarked  that  the  augmentation  of  hardness,  of  density,  and 
of  chemical  indifference  which  is  seen  in  this  last  species,  is 
doubtless  to  be  ascribed  to  a  more  elevated  equivalent,  or,  in 
other  words,  to  a  more  condensed  molecule.  These  different 
degrees  of  condensation,  which  are  constantly  kept  in  view  in  the 
study  of  organic  chemistry,  are  besides,  as  I  have  already  else- 
where shown,  of  great  importance  in  mineralogy,  and  will  form 
the  basis  of  a  new  system  of  classification,  which  will  be  at  the 
same  time  chemical  and  natural-historical.  (Comptes  Rendus, 
1855,  Vol  XLI.  page  79.)  The  different  rhombohedral  carbon- 
spars,  kyanite  and  sillimanite,  hornblende  and  pyroxene,  offer 
in  like  manner  examples  of  different  degrees  of  condensation, 
and  by  their  chemical  composition  belong  to  series  the  terms 
of  which,  like  those  of  the  hydrocarbons  nC2H2,  are  both 
homologues  and  multiples  of  the  first  term.  At  the  same  time 
each  one  of  these  carbonates  and  silicates  belongs  to  another 
possible  series,  the  terms  of  which  differ  by  nM202,  corre- 
sponding to  more  or  less  basic  salts." 

"Meionite,  with  the  oxygen  ratios  3:  2:  1,  is  the  most 
basic  term  known  of  the  series  of  the  wernerites  (scapolites). 
The  proportion  of  silica  in  these  minerals  augments  until  we 
reach  in  dipyre  the  ratios  6:2:1,  with  a  density  which  does 
not  exceed  2.66.  "We  might  then  expect  to  find  a  silicate 
which  should  be  to  dipyre  what  zoisite  or  saussurite  is  to 
meionite,  and  Mr.  Damour  has  recently  had  the  good  fortune 
to  meet  with  such  a  mineral  in  a  specimen  of  jade  from  China, 
of  which  he  has  given  us  the  description  and  the  analysis. 
(Comptes  Renflus,  May  4,  1863.)  This  substance  closely 
resembles  in  its  physical  and  chemical  characters  the  saussurite 
or  jade  from  Monte  Rosa,  of  which  it  has  the  density,  3.34. 
It  is  a  silicate  of  alumina,  lime,  and  soda,  and  gives  the  same 
empirical  formula  as  dipyre.  We  may  expect  to  find  between 
saussurite  and  this  new  species,  to  which  Damour  gives  the 
name  of  jadeite,  other  jades  having  formulas  which  will  corre- 
spond with  the  wernerites  intermediate  between  meionite  and 


XVII.]  CONSTITUTION  AND  VOLUME  OF  MINERAL  SPECIES.   447 

dipyre By  its   hardness,   its  specific  gravity,  and   its 

indifference  to  acids,  jadeite  is  completely  separated  from  the 
wernerite  group,  and  takes  its  place  alongside  of  zoisite  or  saus- 
surite,  with  the  garnets,  idocrase,  and  epidotes.  The  following 
table  will  serve  to  show  the  relations  of  the  new  species  :  — 

Density  (about) 
2.7  3.3 

Oxygen  ratio  3:2:1.    .    .    .    Meionite     .    Saussurite. 
Oxygen  ratio  6:2:1.    .    .    .    Dipyre    .    .    Jadeite." 

[The  hardness  of  jadeite,  according  to  Damour,  is  between 
that  of  orthoclase  and  quartz.  It  is  lamellar  in  structure  and 
exhibits  two  axes  of  polarization.  Uidike  saussurite,  it  is  not 
attacked  by  acids  after  fusion,  —  a  fact  which  is  to  be  ascribed 
to  the  large  proportion  of  silica  which  it  contains.] 


[Professor  J.  P.  Cooke  described,  in  1860  (American  Journal 
of  Science  (2),  XXX.  194),  some  curious  examples  in  the 
crystallized  alloys  of  antimony  and  zinc,  of  considerable  varia- 
tions in  composition  without  change  in  crystalline  form.  These 
cases,  as  remarked  by  him,  do  not  come  within  the  limits  of 
isomorphism  as  generally  understood,  and  hence  he  concludes 
that  "  the  composition  of  a  mineral  species  may  be  modified 
by  an  actual  variation  in  the  proportions  of  its  constituents." 
These  alloys  of  varying  composition  are  to  be  regarded  in  part  as 
examples  of  a  progressive  series  of  isomorphous  compounds  of 
antimony  and  zinc,  of  high  equivalent,  differing  from  each  other 
by  nZn2,  and  in  part,  doubtless,  as  crystalline  mixtures  of  these 
isomorphous  homologous  species.  The  principle  embodied  in 
the  conception  advanced  by  Professor  Cooke,  and  rightly  re- 
garded by  him  of  great  importance  to  a  correct  science  of  min- 
eralogy, he  has  named  allomerism.  It  is  evidently  a  case  of 
homologous  and  isomorphous  relations  between  members  of  a 
progressive  series,  —  a  general  principle  upon  which  I  have  in- 
sisted throughout  the  pages  of  this  paper,  and  which  includes 
the  polymeric  isomorphism  of  Scheerer.] 


XVIII. 

THOUGHTS    ON    SOLUTION   AND    THE 
CHEMICAL   PROCESS. 

(1854.) 

This  paper  appeared  in  the  American  Journal  of  Science  for  January,  1854,  and  also 
in  the  Chemical  Gazette  for  1855,  page  90. 

BY  solution,  as  distinguished  from  fusion  or  volatilization, 
we  understand  in  chemistry  the  production  of  a  homogeneous 
liquid  by  the  combination  of  two  or  more  bodies,  one  of  which 
must  itself  be  in  a  liquid  state,  while  the  others  may  be  liquid, 
solid,  or  gaseous.  The  solvent  action  of  acids  and  alkalies 
upon  bodies  insoluble  in  water  is  by  all  admitted  to  be  chemi- 
cal in  its  nature ;  but,  according  to  Leopold  Gmelin,  "  mixtures 
of  liquids,  and  solutions  of  solids  in  liquids  (as  of  acids,  alka- 
lies, salts,  oils,  etc.,  in  water  and  alcohol),  are,  by  Berzelius, 
Mitscherlich,  Dumas,  and  others  of  the  most  distinguished 
modern  chemists,  regarded  as  not  chemical  unless  they  take  place 
in  definite  proportions."  "  Mitscherlich  attributes  such  unions 
to  adhesion,  Dumas  to  a  solvent  power  intermediate  between 
cohesion  and  (chemical)  affinity,  and  Berzelius  refers  them  to  a 
modification  of  affinity,  while  proper  chemical  combinations  ac- 
cording to  him  result,  not  from  affinity,  but  from  electrical  at- 
traction." (Gmelin's  Handbook,  English  ed.,  Vol.  I.  p.  34.) 

The  learned  author  of  the  Handbook  objects  to  these  views 
that  "  they  restrict  the  idea  of  a  chemical  compound  within 
too  narrow  limits,"  and  he  elsewhere  implies  that  the  force 
which  produces  solution  is  a  weak  degree  of  chemical  affinity. 
(Ibid.,  Vol.  I.  p.  70.)  The  judicious  Turner  also  speaks  of  ordi- 


XVIIL]        SOLUTION  AND  THE  CHEMICAL  PROCESS.  449 

nary  solutions  as  instances  of  chemical  union ;  *  and  Mr.  J.  J. 
Griffin  has  insisted  upon  the  same  view.t  As  these  writers 
have  not,  however,  sufficiently  dwelt  upon  the  important  prin- 
ciple, rejected  by  so  many  names  of  authority,  that  all  solution 
is  chemical  union,  we  propose  to  offer  some  considerations  upon 
aqueous  solution,  and  endeavor  to  show  that  the  process  pre- 
sents all  the  phenomena  of  chemical  combination.  First,  in 
the  fact  that  the  resulting  saturated  solutions  are  perfectly 
homogeneous.  Secondly,  in  the  condensation  and  more  or  less 
perfect  identification  of  volume  (ante,  page  428)  observed  in  the 
process  (some  anhydrous  salts  dissolve  in  water  without  in- 
creasing its  volume).  Thirdly,  in  the  change  of  temperature 
which  attends  the  process;  thus  oil  of  vitriol,  hydrate  of 
potash,  and  many  anhydrous  salts  evolve  heat  when  dissolved 
in  water,  while  sal-ammoniac,  nitre,  and  many  hydrous  salts 
produce  cold  by  their  solution.  Fourthly,  in  the  change  of 
color  which  attends  the  solution  of  some  salts,  as  the  chlorides 
of  nickel,  cobalt,  and  copper. 

It  must  not  be  forgotten  that  the  liquid  state  of  these  aque- 
ous combinations  is  often  an  accident  of  temperature ;  alum 
and  the  rhombic  phosphate  of  soda  are  liquids  at  212°  F.,  and 
bi-hydrated  sulphuric  acid  is  a  crystalline  solid  below  46°  F. 
The  ease  with  which  many  of  these  compounds  are  destroyed 
by  evaporation,  and  even  by  changes  of  temperature,  is  not  to 
be  urged  as  an  objection  to  the  chemical  nature  of  the  union. 
We  need  only  compare  the  corresponding  silver-salts  with  the 
chloride  and  iodide  of  gold,  or  the  hydrochlorates  of  morphia 
and  ammonia  with  those  of  caffeine  and  piperine,  which  lose 
their  acid  by  a  gentle  heat,  to  learn  how  variable  is  the  stability 
of  admitted  chemical  compounds.  Chemical  affinity  may  be 
very  feeble  in  degree. 

According  to  Gay-Lussac,  one  part  of  oil  of  vitriol  will  ab- 
sorb from  air  saturated  with  moisture  fifteen  parts  of  water, 
or  more  than  eighty  equivalents  ;  terchloride  of  arsenic  re- 
quires eighteen  equivalents  of  water  to  dissolve  it,  and  the 

*  Elements  of  Chemistry,  7th  ed.,  p.  139. 

t  L.,  E.  and  D.  Phil.  Mag.  (3),  Vol.  XXIX.  p.  299. 

CO 


450  SOLUTION  AND  THE   CHEMICAL  PROCESS.        [XVIII. 

saturated  solution  unites  with  as  much  more  water,  evolving 
heat  and  forming  a  stable  solution.*  According  to  the  ex- 
periments of  Mr.  Griffin  in  the  paper  cited  above,  the  conden- 
sation which  takes  place  in  the  solution  of  the  acid  is  still 
perceptible  with  6,000  equivalents  of  water  to  one  of  S03. 
There  appears,  however,  to  be  with  many  bodies  a  limit  be- 
yond which  the  affinity  for  water  is  satisfied,  and  the  liquids 
being  then  mechanically  mixed,  gradually  separate  by  reason 
of  their  difference  in  density,  as  is  observed  in  dilute  alcohol, 
and  probably  in  some  saline  solutions  t  and  in  metallic  alloys. 

Solution  is  a  result  of  that  tendency  in  nature  which  con- 
stantly leads  to  unity,  condensation,  identification.  I  have 
elsewhere,  with  Kant,  defined  chemical  union  to  be  inter- 
penetration,  but  the  conception  is  mechanical,  and  therefore 
fails  to  give  an  adequate  idea.  The  definition  of  Hegel,  that 
the  chemical  process  is  an  identification  of  the  different  and  a 
differentiation  of  the  identical^  is,  however,  completely  ade- 
quate. Chemical  union  involves  an  identification,  not  only  of 
the  volumes  (interpenetration  mechanically  considered),  but 
of  the  specific  characters  of  the  combining  bodies,  which  are 
lost  in  those  of  the  new  species.  Such  is  equally  the  case  in 
aqueous  solution,  and  we  may  say  that  all  chemical  union  is 
nothing  else  than  solution ;  the  uniting  species  are,  as  it  were, 
dissolved  in  each  other,  for  solution  is  mutual. 

Solution  being,  then,  identification,  the  discussion  as  to 
whether  metallic  chlorides  are  changed  into  hydrochlorates 
when  dissolved  in  water,  is  meaningless.  Such  a  solution  is  a 

*  Penny  and  Wallace,  L.,  E.  and  D.  Phil.  Mag.,  November,  1852,  page  363. 

t  See  Gmelin's  Handbook,  Eng.  ed.,  Vol.  1.  p.  111.  Gmelin  throws  a 
doubt  npon  these  experiments  ;  but  the  satisfactory  results  obtained  on  a 
large  scale,  in  applying  this  principle  to  the  rectification  of  spirit  of  wine  by 
a  recently  patented  process,  were  communicated  to  the  American  Association 
for  the  Advancement  of  Science,  at  Washington  in  May,  1854,  by  Dr.  L.  D. 
Gale.  [This  is  questionable.] 

t  Stallo's  Philosophy  of  Nature,  page  453 ;  see  also  page  67,  where  Stallo 
insists  upon  the  same  view.  To  Hegel  belongs  the  merit  of  having  first 
among  modern  philosophers  obtained  a  just  conception  of  the  nature  of  the 
chemical  process,  although  in  its  application  he  was  misled  by  the  received 
terminology  of  the  science. 


XVIII.]        SOLUTION  AND  THE   CHEMICAL  PROCESS.  451 

unity,  in  which  we  can  no  more  assert  the  existence  of  the 
chloride  or  of  water,  than  of  chlorine,  hydrochloric  acid,  or  a 
metallic  oxide,  although  these  and  many  others  are  conceiv- 
able results  of  its  differentiation.  If  the  solution  be  one  of 
chloride  of  potassium,  evaporation  resolves  it  into  water  and 
the  chloride,  but  if  chloride  of  aluminum,  it  is  decomposed  by 
boiling  into  water,  hydrochloric  acid,  and  alumina,  or  in  the 
case  of  the  corresponding  magnesian  salt,  into  hydrochloric  acid 
and  an  oxychloride. 

The  precipitation  of  the  sulphates  of  cerium,  lanthanum,  and 
calcium  from  their  solutions  by  heat,  and  of  most  other  salts 
by  cold,  is  chemical  decomposition  or  differentiation.  Dilution 
may  also  effect  decomposition  in  solutions ;  we  have  already 
said  that  the  combination  of  terchloride  of  arsenic,  AsCl3,  with 
36 HO  is  stable  at  ordinary  temperatures,  but  a  further  addi- 
tion of  water  causes  the  solution  to  divide  into  aqueous  hy- 
drochloric acid  and  crystalline  oxide  of  arsenic.  The  precipi- 
tation of  chloride  of  antimony,  and  of  many  salts  of  bismuth 
and  mercury  by  water,  is  an  analogous  process.  This  decom- 
position of  the  solution  of  chloride  of  arsenic  is  an  example 
of  what  is  called  double  elective  affinity  (attractio  electiva  du- 
plex), and  is  generally  explained  by  saying  that  the  attraction 
of  arsenic  for  oxygen,  and  that  of  chlorine  for  hydrogen,  en- 
able the  chloride  and  water  to  decompose  each  other.  But 
these  elemental  species  do  not  exist  in  the  solution,  although 
they  are  possible  results  of  its  decomposition,  and  to  explain 
the  process  in  this  manner  is  to  ascribe  it  to  the  affinities  of 
yet  unformed  species. 

I  have  elsewhere  asserted  that  double  decomposition  always 
involves  union  followed  by  division  (ante,  page  428),  although 
we  cannot  in  every  case  arrest  the  process  at  the  first  stage. 
Under  some  changed  conditions  of  temperature  and  pressure 
the  decomposition  may  be  the  counterpart  of  the  previous 
union,  and  thus  reproduce  the  original  species,  as  in  the  case 
of  mercuric  oxide,  which  is  decomposed  into  mercury  and  oxy- 
gen at  a  temperature  a  little  above  that  at  which  it  was  formed. 
When  the  division  takes  place  in  a  sense  different  from  the 


452  SOLUTION  AND  THE  CHEMICAL  PROCESS.        [XVIII. 

union,  giving  rise  to  new  species,  we  have  double  decomposi- 
tion. Jn  the  case  of  chloride  of  arsenic,  the  aqueous  solution 
exhibits  the  first  stage  of  the  process.  A  similar  condition  of 
unstable  union  is  observed  in  many  other  instances;  thus 
binoxide  of  manganese  gives,  with  cold  hydrochloric  acid,  a 
brown  solution,  but  the  combination  is  by  a  gentle  heat  re- 
solved into  chlorine  gas,  and  a  rose-red  solution  of  protochloride 
of  manganese.  So  a  mixture  of  equivalent  parts  of  chloride 
of  benzoyl  and  benzoate  of  soda  combines  at  a  temperature  of 
130°  C.,  to  form  a  limpid  solution,  and  it  is  only  on  raising 
the  temperature  that  the  precipitation  of  sea-salt  indicates  the 
commencement  of  that  decomposition  which  yields  at  the  same 
time  anhydrous  benzoic  acid.*  It  is  only  when  looked  upon 
as  a  momentary  combination  followed  by  a  decomposition,  that 
the  theory  of  double  decomposition  becomes  intelligible,  and  is 
in  accordance  with  known  facts. 

From  the  narrow  limits  of  temperature  which  often  include 
the  two  processes,  and  from  the  ease  with  which  light,  warmth, 
friction,  and  pressure  excite  the  decomposition  of  such  bodies 
as  the  chloride  of  nitrogen,  the  nitrite  of  ammonia,  the  oxides 
of  chlorine,  and  the  metallic  fulminates,  we  may  conceive  that 
within  still  narrower  limits,  and  under  conditions  as  yet  unde- 
fined, many  bodies  may  exhibit  affinities  for  each  other  which 
are  reversed  by  a  very  slight  change  of  condition.  In  this 
way  we  may  explain  many  of  those  obscure  phenomena  hith- 
erto ascribed  to  action  by  presence  or  catalysis. 

*  Gerhardt,  Ann.  de  Chimie  et  de  Physique,  3m«  Serie,  Tom.  XXXVII. 
page  299. 


XIX. 

ON  THE  OBJECTS  AND  METHOD  OF 
MINERALOGY. 

(1867.) 

This  paper  was  read  before  the  American  Academy  of  Sciences  in  Boston,  January 
8,  1867,  and  published  in  the  American  Journal  of  Science  in  May  of  the  same  year. 

MINERALOGY,  as  popularly  understood,  holds  an  anomalous 
position  among  the  natural  sciences,  and  is  by  many  regarded 
as  having  no  claims  to  be  considered  as  a  distinct  science,  but 
as  constituting  a  branch  of  chemistry.  This  secondary  place  is 
disputed  by  some  mineralogists,  who  have  endeavored  to  base  a 
natural-history  classification  upon  such  characters  as  the  crys- 
talline form,  hardness,  and  specific  gravity  of  minerals.  In  sys- 
tems of  this  kind,  however,  like  those  of  Mohs  and  his  followers, 
only  such  species  as  occur  ready  formed  in  nature  are  compre- 
hended, and  the  great  number  of  artificial  species,  often  closely 
related  to  native  minerals,  are  excluded.  It  may  moreover  be 
said  in  objection  to  these  naturalists,  that,  in  its  wider  sense, 
the  chemical  history  of  bodies  takes  into  consideration  all  those 
characters  upon  which  the  so-called  natural  systems  of  classifi- 
cation are  based.  In  order  to  understand  clearly  the  question 
before  us,  we  must  first  consider  what  are  the  real  objects,  and 
what  the  provinces,  respectively,  of  mineralogy  and  of  chem- 
istry. 

Of  the  three  great  divisions,  or  kingdoms  of  nature,  the  clas- 
sification of  the  vegetable  gives  rise  to  systematic  botany,  that 
of  the  animal  to  zoology,  and  that  of  the  mineral  to  mineralogy, 
which  has  for  its  subject  the  natural  history  of  all  the  forms  of 
unorganized  matter.  The  relations  of  these  to  gravity,  cohe- 


454  OBJECTS  AND   METHOD   OF  MINERALOGY.  [XIX. 

sion,  light,  heat,  electricity,  and  magnetism  belong  to  the  do- 
main of  physics ;  while  chemistry  treats  of  their  relations  to 
each  other,  and  of  their  transformations  under  the  influences 
of  heat,  light,  and  electricity.  Chemistry  is  thus  to  mineralogy 
what  biology  is  to  organography ;  and  the  abstract  sciences, 
physics  and  chemistry,  must  precede,  and  form  the  basis  of  the 
concrete  science,  mineralogy.  Many  species  are  chiefly  distin- 
guished by  their  chemical  activities,  and  hence  chemical  char- 
acters must  be  greatly  depended  upon  in  mineralogical  classifi- 
cation. 

Chemical  change  implies  disorganization,  and  all  so-called 
chemical  species  are  inorganic,  that  is  to  say,  unorganized,  and 
hence  really  belong  to  the  mineral  kingdom.  In  this  extended 
sense,  mineralogy  takes  in  not  only  the  few  metals,  oxides,  sul- 
phides, silicates,  and  other  salts  which  are  found  in  nature,  but 
also  all  those  which  are  the  products  of  the  chemist's  skill.  It 
embraces  not  only  the  few  native  resins  and  hydrocarbons,  but 
all  the  bodies  of  the  carbon  series  made  known  by  the  re- 
searches of  modern  chemistry. 

The  primary  object  of  a  natural  classification,  it  must  be  re- 
membered, is  not,  like  that  of  an  artificial  system,  to  serve  the 
purpose  of  determining  species,  or  the  convenience  of  the  stu- 
dent, but  so  to  arrange  bodies  in  genera,  orders,  and  species  as  to 
satisfy  most  thoroughly  natural  affinities.  Such  a  classification 
in  mineralogy  will  be  based  upon  a  consideration  of  all  the 
physical  and  chemical  relations  of  bodies,  and  will  enable  us  to 
see  that  the  various  properties  of  a  species  are  not  so  many 
arbitrary  signs,  but  the  necessary  results  of  its  constitution.  It 
will  give  for  the  mineral  kingdom  what  the  labors  of  great 
naturalists  have  already  nearly  attained  for  the  vegetable  and 
animal  kingdoms. 

Oken  saw  the  necessity  of  thus  enlarging  the  bounds  of  min- 
eralogy, and  in  his  Physiophilosophy  attempted  a  mineralogical 
classification  ;  but  it  is  based  on  fanciful  and  false  analogies, 
with  but  little  reference  either  to  physical  or  chemical  charac- 
ters, and  in  the  present  state  of  our  knowledge  is  valueless, 
except  as  an  effort  in  the  right  direction,  and  an  attempt  to 


XIX.]  OBJECTS  AND   METHOD   OF  MINERALOGY.  455 

give  to  mineralogy  a  natural  system.  "With  similar  views  as  to 
the  scope  of  the  science,  and  with  far  higher  and  juster  concep- 
tions of  its  method,  Stallo,  in  his  Philosophy  of  Nature,  has 
touched  the  questions  before  us,  and  has  attempted  to  show 
the  significance  of  the  relations  of  the  metals  to  cohesion,  grav- 
ity, light,  and  electricity,  but  has  gone  no  further. 

In  approaching  this  great  problem  of  classification,  we  have 
to  examine,  first,  the  physical  condition  and  relations  of  each 
species,  considered  with  relation  to  gravity,  cohesion,  light, 
heat,  electricity,  and  magnetism;  secondly,  the  chemical  his- 
tory of  the  species,  in  which  are  to  be  considered  its  nature,  as 
elemental  or  compound,  its  chemical  relations  to  other  species, 
and  these  relations  as  modified  by  physical  conditions  and 
forces.  The  quantitative  relation  of  one  mineral  (chemical) 
species  to  another  is  its  equivalent  weight,  and  the  chemical 
species,  until  it  attains  to  individuality  in  the  crystal,  is  essen- 
tially quantitative. 

It  is  from  all  the  above  data,  which  would  include  the  whole 
physical  and  chemical  history  of  inorganic  bodies,  that  a  nat- 
ural system  of  mineralogical  classification  is  to  be  built  up. 
Their  application  may  be  illustrated  by  a  few  points  drawn 
from  the  history  of  certain  natural  families. 

The  variable  relations  to  space  of  the  empirical  equivalents 
of  non-gaseous  species,  or,  in  other  words,  the  varying  equiva- 
lent volume  (obtained  by  dividing  their  empirical  equivalent 
weights  by  the  specific  gravity),  shows  that  there  exist  in  differ- 
ent species  very  unlike  degrees  of  condensation.  At  the  same 
time  we  are  led  to  the  conclusion  that  the  molecular  constitu- 
tion of  gems,  spars,  and  ores  is  such  that  those  bodies  must  be 
represented  by  formulas  not  less  complex,  and  with  equivalent 
weights  far  more  elevated  than  those  usually  assigned  to  the 
polycyanides,  the  alkaloids,  and  the  proximate  principles  of 
plants.  (Ante,  pages  434  and  441.)  To  similar  conclusions 
conduce  also  the  researches  on  the  specific  heat  of  compounds. 

There  probably  exists  between  the  true  equivalent  weights 
of  non-gaseous  species  and  their  densities  a  relation  as  simple 
as  that  between  the  equivalent  weights  of  gaseous  species  and 


456  OBJECTS  AND   METHOD  OF  MINERALOGY.  [XIX. 

their  specific  gravities.  The  gas  or  vapor  of  a  volatile  "body 
constitutes  a  species  distinct  from  the  same  body  in  its  liquid 
or  solid  state,  the  chemical  formula  of  the  latter  being  some 
multiple  of  the  first;  and  the  liquid  and  solid  species  them- 
selves often  constitute  two  distinct  species  of  different  equiva- 
lent weights.  In  the  case  of  analogous  volatile  compounds, 
as  the  hydrocarbons  and  their  derivatives,  the  equivalent 
weights  of  the  liquid  or  solid  species  approximate  to  a  con- 
stant quantity,  so  that  the  densities  of  those  species,  in  the 
case  of  homologous  or  related  alcohols,  acids,  ethers,  and  gly- 
cerides,  are  subject  to  no  great  variation.  These  non-gaseous 
species  are  generated  by  the  chemical  union,  or  identification, 
of  a  number  of  volumes  or  equivalents  of  the  gaseous  species, 
which  number  varies  inversely  as  the  density  of  these  species. 
It  follows  from  this  that  the  equivalent  weights  of  the  liquid 
and  solid  alcohols  and  fats  must  be  so  high  as  to  be  a  common 
measure  of  the  vapor-equivalents  of  all  the  bodies  belonging  to 
these  series.  The  empirical  formula  CmH110C12,  which  is  the 
lowest  one  representing  the  tristearic  glyceride  (ordinary  stea- 
rine),  is  probably  far  from  representing  the  true  equivalent 
weight  of  this  fat  in  its  liquid  or  solid  state ;  and  if  it  should 
hereafter  be  found  that  its  density  corresponds  to  six  times 
the  above  formula,  it  would  follow  that  liquid  acetic  acid, 
whose  density  differs  but  slightly  from  that  of  fused  stearine, 
must  have  a  formula  and  an  equivalent  weight  about  one 
hundred  times  that  which  we  deduce  from  the  density  of 
acetic-acid  vapor,  C4H404. 

Starting  from  these  high  equivalent  weights  of  liquid  and 
solid  hydrocarbonaceous  species,  and  their  correspondingly 
complex  formulas,  we  become  prepared  to  admit  that  other 
orders  of  mineral  species,  such  as  oxides,  silicates,  carbonates, 
and  sulphides,  have  formulas  and  equivalent  weights  corre- 
sponding to  their  still  higher  densities ;  and  we  proceed  to 
apply  to  these  bodies  the  laws  of  substitution,  homology,  and 
polymerism,  which  have  so  long  been  recognized  in  the  chemi- 
cal study  of  the  members  of  the  hydrocarbon  series.  The 
formulas  thus  deduced  for  the  native  silicates  and  carbon-spars, 


XIX.]  OBJECTS  AND   METHOD   OF  MINERALOGY.  457 

show  that  these  polybasic  salts  may  contain  many  atoms  of 
different  bases,  and  their  frequently  complex  and  varying 
constitution  is  thus  rendered  intelligible.  In  the  application 
of  the  principle  of  chemical  homology,  we  tind  a  ready  and 
natural  explanation  of  those  variations  within  certain  limits, 
occasionally  met  with  in  the  composition  of  certain  crystalline 
silicates,  sulphides,  etc.;  from  which  some  have  conjectured  the 
existence  of  a  deviation  from  the  law  of  definite  proportions, 
in  what  is  only  an  expression  of  that  law  in  a  higher  form. 

The  principle  of  polymerism  is  exemplified  in  related  mineral 
species,  such  as  meionite  and  zoisite,  dipyre  and  jadeite,  horn- 
blende and  pyroxene,  calcite  and  aragonite,  opal  and  quartz,  in 
the  zircons  of  different  densities,  and  in  the  various  forms  of 
titanic  acid  and  of  carbon,  whose  relations  become  at  once  in- 
telligible if  we  adopt  for  these  species  high  equivalent  weights 
and  complex  molecules.  The  hardness  of  these  isomeric  or 
allotropic  species,  and  their  indifference  to  chemical  reagents, 
increase  with  their  condensation,  or,  in  other  words,  vary  in- 
versely as  their  empirical  equivalent  volumes  ;  so  that  we  here 
find  a  direct  relation  between  chemical  and  physical  prop- 
erties. 

It  is  in  these  high  chemical  equivalents  of  the  species,  and 
in  certain  ingenious  but  arbitrary  assumptions  of  numbers, 
that  is  to  be  found  an  explanation  of  the  results  obtained  by 
Playfair  and  Joule  in  comparing  the  volumes  of  various  solid 
species  with  that  of  ice ;  whose  constitution  they  assume  to  be 
represented  by  HO,  instead  of  a  high  multiple  of  this  formula. 
The  recent  ingenious  but  fallacious  speculations  of  Dr.  Mac- 
vicar,  who  has  arbitrarily  assumed  comparatively  high  equiva- 
lent weights  for  mineral  species,  and  has  then  endeavored, 
by  conjectures  as  to  the  architecture  of  crystalline  molecules, 
to  establish  relations  between  his  complex  formulas  and  the 
regular  solids  of  geometry,  are  curious  but  unsuccessful  at- 
tempts to  solve  some  of  the  problems  whose  significance  I  have 
here  endeavored  to  set  forth.  I  am  convinced  that  no  geo- 
metrical grouping  of  atoms,  such  as  are  imagined  by  Macvicar 
and  by  Gaudin,  can  ever  give  us  an  insight  into  the  way  in 
20 


458  OBJECTS  AND   METHOD   OF  MINERALOGY.  [XIX. 

which  Nature  builds  up  her  units,  by  interpenetration  and 
identification,  and  not  by  juxtaposition  of  the  chemical  ele- 
ments. 

None  of  the  above  points  are  presented  as  new,  though  they 
are  for  the  greater  part,  I  believe,  original  with  myself,  and 
have  been  from  time  to  time  brought  forward  and  maintained, 
with  numerous  illustrations,  chiefly  in  the  American  Journal 
of  Science,  since  March,  1853,  when  my  paper  on  the  Theory 
.  of  Chemical  Changes  and  Equivalent  Volumes  (ante,  page  426) 
was  there  published.  I  have,  however,  thought  it  well  to  pre- 
sent these  views  in  a  connected  form,  as  exemplifying  my 
notion  of  some  of  the  principles  which  must  form  the  basis 
of  a  true  mineralogical  classification. 


XX. 


THEORY  OF  TYPES  IN   CHEMISTRY. 

(1848-1861.) 

In  the  years  1848  - 1854  I  published  in  the  American  Journal  of  Science  several  essays 
on  the  theory  of  chemical  types  and  on  related  questions  in  the  science.  The  first,  on 
the  Anomalies  in  the  Atomic  Volumes  of  Sulphur  and  Nitrogen  and  on  Chemical  Classi- 
fication, appeared  in  September,  1848,  and  was  followed  in  May  and  July,  1849,  by  a 
paper  on  Some  Points  to  be  considered  in  Chemical  Classification.  In  January,  1850, 
appeared  a  pai>er  on  the  Constitution  of  Leucine,  with  Remarks  on  the  late  Researches 
of  Wurtz  ;  and  in  March,  1852,  one  on  the  Compound  Ammonias  and  the  Bodies  of  the 
Cacodyle  Series.  In  March,  1854,  I  published  a  summary  of  the  views  embodied  in 
the  preceding  papers,  commenting  especially  on  the  first  one,  in  an  essay  on  The 
Theoretical  Relations  of  Water  and  Hydrogen,  and  vindicating  for  myself  the  priority 
in  those  views  of  chemical  theory  which  had  since  my  announcement  of  them  been 
adopted  by  Gerhardt,  Williamson,  Wurtz,  and  other  chemists.  The  publication  by 
Wurtz  of  a  criticism  of  Kolbe,  in  1860,  led  me  to  write  the  following  paper  on  the 
Theory  of  Types  in  Chemistry,  in  which  I  have  concisely  traced  the  history  of  the  de- 
velopment of  my  views.  It  appeared  in  the  Canadian  Journal  for  March,  1861,  and  in 
the  American  Journal  of  Science  for  the  same  month  of  the  same  year.  I  have,  in  re- 
printing it,  added  an  appendix  on  Nitrogen  and  Nitrification. 

IN  the  Annalen  der  Chemie  und  Pharmacie  for  March,  1860 
(CXIII.  293),  Mr.  Kolbe  has  published  a  paper  on  the  natural 
relations  between  mineral  and  organic  compounds,  considered 
as  a  scientific  basis  for  a  new  classification  of  the  latter.  He 
objects  to  the  four  types  admitted  by  Gerhardt,  namely,  hydro- 
gen, hydrochloric  acid,  water,  and  ammonia,  that  they  sustain 
to  organic  compounds  only  artificial  and  external  relations,  while 
he  conceives  that  between  these  and  certain  other  bodies  there 
are  natural  relations,  having  reference  to  the  origin  of  the 
organic  species.  Starting  from  the  fact  that  all  the  bodies  of ' 
the  carbon  series  found  in  the  vegetable  kingdom  are  derived 
from  carbonic  acid,  with  the  concurrence  of  water,  he  proceeds 
to  show  how  all  the  compounds  of  carbon,  hydrogen,  and 
oxygen  may  be  derived  from  the  type  of  an  oxide  of  carbon, 
which  is  either  C204,  C^  or  the  hypothetical  C20. 


460      '  THEORY  OF  TYPES  IN  CHEMISTRY.        [XX. 

When  in  the  former  we  replace  one  atom  of  oxygen  by  one 
of  hydrogen  we  have  C203H,  or  anhydrous  formic  acid  ;  the 
replacement  of  a  second  equivalent  would  yield  C202H2,  or 
the  unknown  formic  aldehyde  ;  a  third,  C2OH3,  the  oxide  of 
methyle  ;  and  a  fourth,  C2H4,  or  formene.  By  substituting 
methyle  for  one  or  more  atoms  of  hydrogen  in  the  previous 
formula,  we  obtain  those  of  the  corresponding  bodies  of  the 
vinic  series,  and  it  will  be  readily  seen  that  by  introducing  the 
higher  alcoholic  radicles  we  may  derive  from  C204  the  formulas 
of  all  the  alcoholic  series.  A  grave  objection  to  this  view  is, 
however,  found  in  the  fact  that  while  this  compound  may  be 
made  the  type  of  the  aldehydes,  acetones,  and  hydrocarbons,  it 
becomes  necessary  to  assume  the  hypothetical  C202,HO,  as  the 
type  of  the  acids  and  alcohols.  Oxide  of  carbon,  C202,  is, 
according  to  Kolbe,  to  be  received  as  the  type  of  hydrocarbons 
like  olefiant  gas  (C2HMe),  while  C20,  in  which  ethyle  replaces 
oxygen,  is  C6H5,  or  lipyle,  the  supposed  triatomic  base  of 
glycerine. 

The  monobasic  organic  acids  are  thus  derived  from  one  atom 
of  C204,  while  the  bibasic  acids,  like  the  succinic,  are  by 
Kolbe  deduced  from  a  double  molecule,  C408,  and  tribasic 
acids,  like  the  citric,  from  a  triple  molecule,  C6012.  He  more- 
over compares  sulphuric  acid  to  carbonic  acid,  and  derives  from 
it  by  substitution  the  various  sulphuric  organic  compounds. 
Ammonia,  arseniuretted  and  phosphuretted  hydrogen,  are  re- 
garded as  so  many  types ;  and  by  an  extension  of  his  view  of 
the  replacement  of  oxygen  by  electro-positive  groups,  the 
ethylides,  ZnEt,  PbEt2,  and  BiEt3,  are,  by  Kolbe,  assimilated 
to  the  oxides,  ZnO,  Pb02,  and  Bi03. 

Ad.  Wurtz,  in  the  Repertoire  de  Chimie  Pure  for  October, 
1860,  has  given  an  analysis  of  Kolbe's  memoir  (to  which,  not 
having  the  original  before  me,  I  am  indebted  for  the  preceding 
sketch),  and  follows  it  by  a  judicious  criticism.  While  Kolbe 
adopts  as  types  a  number  of  mineral  species,  including  the 
oxides  of  carbon,  of  sulphur,  and  the  metals,  Wurtz  would 
maintain  but  three,  hydrogen  (H2),  water  (H202),  and  ammonia 
(NH3) ;  and  these  three  types,  as  he  endeavored  to  show  in 


XX.]  THEORY   OF  TYPES  IN   CHEMISTRY.  4G1 

1855,  represent  different  degrees  of  condensation  of  matter. 
The  molecule  of  hydrogen,  H2  =  (M2),  corresponding  to  four 
volumes,  combines  with  two  volumes  of  oxygen  (02)  to  form 
four  volumes  of  water,  and  may  thus  be  regarded  as  condensed 
to  one  half  in  its  union  with  oxygen,  and  derived  from  a 
double  molecule,  M2M2.  In  like  manner  four  volumes  of 
ammonia  contain  two  volumes  of  nitrogen  and  six  of  hydro- 
gen, which,  being  reduced  to  one  third,  correspond  to  a  triple 
molecule,  M3M3,  so  that  these  three  types  and  their  multiples 
are  reducible  to  that  of  hydrogen  more  or  less  condensed. 
(Wurtz,  Annales  de  Chimie  et  de  Physique  (3),  XLIV.  304.) 

As  regards  the  rejection  of  water  as  a  type  of  organic  com- 
pounds, and  the  substitution  of  carbonic  acid,  founded  upon 
the  consideration  that  these  in  nature  are  derived  from  C204, 
Wurtz  has  well  remarked  that  water,  as  the  source  of  hydro- 
gen, is  equally  essential  to  their  formation,  and,  indeed,  that 
the  carbonic  anhydride  CaO^  like  all  other  anhydrous  acids, 
may  be  regarded  as  a  simple  derivative  of  the  water-type. 
Having  then  adopted  the  notion  of  referring  a  great  variety  of 
bodies  to  a  mineral  species  of  simple  constitution,  water  is  to 
be  preferred  to  carbonic  anhydride,  first,  because  we  can  com- 
pare with  it  many  mineral  compounds  which  can  with  diffi- 
culty be  compared  with  carbonic  acid ;  and,  secondly,  because 
the  two  atoms  of  water  being  replaceable  singly,  the  mode  of 
derivation  of  a  great  number  of  compounds  (acids,  alcohols, 
ethers,  etc.)  is  much  more  simple  and  natural  than  from  car- 
bonic acid.  As  Wurtz  happily  remarks,  Kolbe  has  so  fully 
adopted  the  theory  of  types,  that  he  wishes  to  multiply  them, 
and  even  admits  condensed  types,  which  are,  however,  mole- 
cules of  carbonic  acid,  and  not  of  water;  "he  combats  the 
types  of  Gerhardt  and  at  the  same  time  counterfeits  them." 

Thus  far  we  are  in  accordance  with  Mr.  Wurtz,  who  has 
shown  himself  one  of  the  ablest  and  most  intelligent  ex- 
pounders of  this  doctrine  of  molecular  types  as  above  defined  : 
—  now  almost  universally  adopted  by  chemists.  He  writes, 
"  To  my  mind  this  idea  of  referring  to  water,  taken  as  a  type, 
a  very  great  number  of  compounds,  is  one  of  the  most  beauti- 


462        THEORY  OF  TYPES  IN  CHEMISTRY.        [XX. 

ful  conceptions  of  modern  chemistry."  (Repertoire  de  Chimie 
Pure,  1860,  page  359.)  And  again,  he  declares  that  the  idea 
of  regarding  both  water  and  ammonia  as  representatives  of  the 
hydrogen-type  more  or  less  condensed,  to  be  so  simple  and  so 
general  in  its  application  that  it  is  worthy  "to  form  the  basis 
of  a  system  of  chemistry."  (Ibid.,  page  356.) 

We  have  in  this  theory  two  important  conceptions  :  the  first 
is  that  of  hydrogen  and  water  regarded  as  types  to  which  both 
mineral  and  organic  compounds  may  be  referred ;  and  the  sec- 
ond is  the  notion  of  condensed  and  derived  types,  according  to 
which  we  not  only  assume  two  or  three  molecules  of  hydrogen 
or  water  as  typical  forms,  but  even  look  on  water  as  the  de- 
rivative of  hydrogen,  which  is  itself  the  primal  type. 

As  to  the  history  of  these  ideas,  Wurtz  remarks  that  the 
proposition  enunciated  by  Kolbe,  that  all  organic  bodies  are 
derived  by  substitution  from  mineral  compounds,  is  not  new, 
but  known  in  the  science  for  about  ten  years.  "  Williamson 
was  the  first  who  said  that  alcohol,  ether,  and  acetic  acid  were 
comparable  to  water,  —  organic  waters.  Hoffman  and  myself 
had  already  compared  the  compound  ammonias  to  ammonia 
itself.  ....  To  Gerhardt  belongs  the  merit  of  generalizing 
these  ideas,  of  developing  them,  and  supporting  them  with  his 
beautiful  discovery  of  anhydrous  monobasic  acids.  Although 
he  did  not  introduce  into  the  science  the  idea  of  types,  which 
belongs  to  M.  Dumas,  he  gave  it  a  new  form,  which  is  ex- 
pressed and  essentially  reproduced  by  the  proposition  of  Kolbe. 
Gerhardt  reduced  all  organic  bodies  to  four  types,  —  hy- 
drogen, hydrochloric  acid,  water,  and  ammonia."  (Ibid.,  page 
355.) 

The  historical  inaccuracies  of  the  above  quotation  are  the 
more  surprising,  since  in  March,  1854,  I  published  in  the 
American  Journal  of  Science  (XVII.  194)  a  concise  account 
of  the  progress  of  these  views.  This  paper  was  republished 
in  the  Chemical  Gazette  (1854,  page  181),  and  copies  of  it 
were  by  myself  placed  in  the  hands  of  most  of  the  distin- 
guished chemists  of  England,  France,  and  Germany.  In  this 
paper  I  have  shown  that  the  germ  of  the  idea  of  mineral 


XX.]  THEORY   OF  TYPES  IN   CHEMISTRY.  463 

types  is  to  be  found  in  an  essay  of  Auguste  Laurent  (Sur  les 
Combinaisons  Azote"es,  Ann.  de  Chimie  et  Physique,  Novem- 
ber, 1846),  where  he  showed  that  alcohol  may  be  looked  upon 
as  water  (H202)  in  which  ethyle  replaces  one  atom  of  hydrogen, 
and  hydric  ether  as  the  result  of  a  complete  substitution  of 
the  hydrogen  by  a  second  atom  of  ethyle.  Hence  he  observed 
that  while  ether  is  neutral,  alcohol  is  monobasic  and  the  type 
of  the  monobasic  vinic  acids,  as  water  is  the  type  of  bibasic 
acids.  In  extending  and  developing  this  idea  of  Laurent's,  I 
insisted  in  March,  1848,  and  again  in  January,  1850,  upon  the 
relation  between  the  alcohols  and  water  as  one  of  homology, 
water  being  the  first  term  in  the  series,  and  H2  being  in  like 
manner  the  homologue  of  acetene  and  formene ;  while  the 
bases  of  Wurtz  were  said  to  "  sustain  to  their  corresponding 
alcohols  the  same  relation  .that  ammonia  does  to  water."  (Am. 
Journal  of  Science,  V.  265  ;  IX.  65  ;  XIII.  206.) 

In  a  notice  of  his  essay,  published  in  September,  1848 
(Ibid.,  VI.  173),  I  endeavored  to  show  that  Laurent's  view 
might  be  further  extended,  so  as  to  include  in  the  type  of 
water  "  all  those  saline  combinations  (acids)  which  contain  oxy- 
gen "  ;  and  in  a  paper  read  before  the  American  Association  for 
the  Advancement  of  Science  at  Philadelphia,  in  September, 
1848,  I  further  suggested  that  as  many  neutral  oxygenized 
compounds  which  do  not  possess  a  saline  character  are  deriva- 
tives of  acids  which  are  referable  to  the  type  H202,  "  we  may 
regard  all  oxygenized  bodies  as  belonging  to  this  lype"  which  I 
further  showed  in  the  same  essay  to  be  but  a  derivative  of  the 
primal  type  Hg.  To  this  I  referred  all  hydrocarbons  and  their 
chlorinized  derivatives,  as  also  the  volatile  alkaloids,  which 
were  regarded  as  "  amidized  species "  of  the  hydrocarbons,  in 
which  the  residue  amidogen,  NH2,  replaces  an  atom  of  H  or 
Cl,  or,  what  is  equivalent,  the  residue  NH  is  substituted  for 
02  in  the  corresponding  alcohols.  (Ibid.,  VIII.  92.) 

In  the  paper  published  in  September,  1848,  I  showed  that 
while  water  is  bibasic,  the  acids  which  like  hypochlorous  and 
nitric  acids  were  derived  from  it  by  a  simple  substitution  of  Cl 
and  NO^  for  H,  were  necessarily  monobasic,  and  I  then  pointed 


464        THEORY  OF  TYPES  IN  CHEMISTRY.        [XX. 

out  the  possible  existence  of  the  nitric  anhydride  (N04)202, 
which  was  soon  after  discovered  by  Deville.  Gerhardt  at 
this  time  denied  the  existence  of  anhydrides  of  the  monobasic 
acids,  regarding  anhydrides  as  characteristic  of  polybasis  acids, 
and  indeed  was  only  led  to  adopt  my  views  by  the  discovery 
of  the  very  anhydrides  whose  formation  I  had  foreseen.* 

In  explaining  the  origin  of  bibasic  acids  I  described  them 
as  produced  by  the  replacement,  in  a  second  equivalent  of 
water,  of  an  atom  of  hydrogen  by  a  monobasic  saline  group ; 
thus  sulphuric  acid  would  be  (S2H06H)02.  Tribasic  acids  in 
like  manner  are  to  be  regarded  as  derived  from  a  third  equiva- 
lent of  water  in  which  a  bibasic  residue  replaces  an  atom  of 
hydrogen.  The  idea  of  polymeric  types  was  further  illus- 
trated in  the  same  paper,  where  three  hydrogen  types  were 
proposed  (HH),  (H2H2),  and  (H3H3),  corresponding  to  the  chlo- 
rides MCI,  MC13,  and  MC15 .  It  was  also  illustrated  by  sulphur 
in  its  ordinary  state,  which  I  showed  is  to  be  regarded  as  a 
triple  molecule  S3  (or  S6  =  4  volumes),  and  I  referred  sulphur- 
ous acid  S02  to  this  type,  to  which  also  probably  belongs 
selenic  oxide.  (At  the  same  time  I  suggested  that  the  odorant 
form  of  oxygen  or  ozone  was  possibly  03.)  Wurtz,  in  his 
memoir,  published  in  1855,  adopts  my  view,  and  makes  sulphur 
vapor  at  400°  C.,  the  type  of  the  triple  molecule.  I  further  sug- 
gested (American  Journal  of  Science,  V.  408;  VI.  172)  that 
gaseous  nitrogen  is  NN",  an  anhydride  amide  or  nitryl,  corre- 
sponding to  nitrite  of  ammonia  (N03,NH40)  —  H404  =  NN. 
This  view  a  late  writer  attributes  to  Gerhardt,  who  adopted  it 
from  me.  (Ann.  de  Chimie  et  Phys.,  LX.  381.)  May  not 
nitrogen  gas,  as  I  have  elsewhere  suggested,  regenerate  under 
certain  conditions,  ammonia  and  a  nitrite,  and  thus  explain 
not  only  the  frequent  formation  of  ammonia  in  presence  of  air 
and  reducing  agents,  but  certain  cases  of  nitrification  1 1 

*  The  anhydrides  of  the  monobasic  acids  correspond  to  two  equivalents  of 
the  acid,  minus  one  of  water,  as  2(C4H404)  — H,0t=  C8H606;  while  one 
equivalent  of  a  bibasic  acid  (itself  derived  from  2Ht02)  loses  one  of  water, 
and  becomes  an  anhydride,  as  C8H200  —  H202  ==  CSO4.  So  that  both  classes 
of  Anhydrides  are  to  be  referred  to  the  type  of  one  molecule  of  water,  H208. 

f  The  formation  qf  a  nitrite  in  the  experiments  of  Cloez  appears  to  be 


XX.]  THEORY  OF  TYPES  IN   CHEMISTRY.  465 

I  endeavored  still  further  to  show  that  hydrogen  is  to  be 
looked  upon  as  the  fundamental  type,  from  which  the  water- 
type  is  derived  by  the  replacement  of  an  atom  of  H  by  the 
residue  H02.  (American  Journal  of  Science,  VIII.  93.)  In 
the  same  way  I  regarded  ammonia  as  water  in  which  the  resi- 
due NH  replaced  Og. 

I  have  always  protested  against  the  view  which  regards  the 
so-called  rational  formulas  as  expressing  in  any  way  the  real 
structure  of  the  bodies  which  are  thus  represented.  These 
formulas  are  invented  to  explain  a  certain  class  of  reactions, 
and  we  may  construct  from  other  points  of  view  other  rational 
formulas  which  are  equally  admissible.  As  I  have  elsewhere 
said,  "the  various  hypotheses  of  copulates  and  radicles  are 
based  upon  the  notion  of  dualism,  which  has  no  other  founda- 
tion than  the  observed  order  of  generation,  and  can  have  no 
place  in  a  theory  of  the  science."  All  chemical  changes  are 
reducible  to  union  (identification)  and  division  (differentiation). 
When  in  these  changes  only  one  species  is  concerned,  we  des- 
ignate the  process  as  metamorphosis,  which  is  either  by  con- 
densation or  by  expansion  (homogeneous  differentiation).  In 
metagenesis,  on  the  contrary,  unlike  species  may  unite,  and  by 
a  subsequent  heterogeneous  differentiation  give  rise  to  new 
species,  constituting  what  is  called  double  decomposition,  the 
results  of  which,  differently  interpreted,  have  given  origin  to 
the  hypothesis  of  radicles  and  the  notion  of  substitution  by 
residues,  to  express  the  relations  between  the  parent  bodies  and 
their  progeny.  The  chemical  history  of  bodies  is  then  a  record 
of  their  changes ;  it  is  in  fact  their  genealogy,  and  in  making 

independent  of  the  presence  of  ammonia,  and  to  require  only  the  elements 
of  air  and  water.  (Comptes  R^ndus,  LXI.  135.)  Some  experiments  now  in 
progress  lead  me  to  conclude  that  the  appearance  of  a  nitrite  in  the  various 
processes  for  ozone  is  due  to  the  power  of  nascent  oxygen  to  destroy  by  oxi- 
dation the  ammonia  generated  by  the  action  of  water  on  nitrogen,  the  nitrous 
nitryl  ;  so  that  the  odor  and  many  of  the  reactions  assigned  to  ozone  or 
nascent  oxygen  are  really  due  to  the  nitrous  acid  which  is  set  free  when  the 
former  encounters  nitrogen  and  moisture.  On  the  other  hand,  nascent  hydro- 
gen, which  readily  reduces  nitrates  and  nitrites  to  ammonia,  by  destroying  the 
regenerated  nitrite  of  the  nitryl,  produces  ammonia  in  many  cases  from  at- 
mospheric nitrogen.  [See  Appendix,  page  470.] 

20*  DD 


466  THEORY  OF  TYPES  IN   CHEMISTRY.  [XX. 

use  of  typical  formulas  to  indicate  the  derivation  of  chemical 
species,  we  should  endeavor  to  show  the  ordinary  modes  of 
their  generation.  [See  the  preceding  papers  XVI.  and  XVIII.] 

Keeping  this  principle  in  mind,  let  us  now  examine  the  theory 
of  the  formation  of  acids.  As  we  have  just  seen,  I  taught  in 
1848  that  the  monobasic,  bibasic,  and  tribasic  acids  are  derived 
respectively  from  one,  two,  and  three  molecules  of  water,  H202. 
Mr.  Wurtz,  seven  years  later,  put  forth  an  analogous  view.  He 
however  supposes  a  monatomic  radicle  P0'4,  a  diatomic  radicle 
P0"3,  and  a  triatomic  radicle  P0'"2,  replacing  respectively  one, 
two,  and  three  atoms  of  hydrogen  in  H202,  H404,  and  H/ >6 ; 
thus  (PO/4H)02,  (PO"3H2)04,  and  (PO"'2H3)06.  These  radicles 
evidently  correspond  to  P05,  which  has  lost  one,  two,  and  three 
atoms  of  oxygen  in  reacting  upon  the  hydrogen  of  the  water- 
types,  and  the  acids  may  be  accordingly  represented  as  formed 
by  the  substitution  of  the  residues  P05  —  0  for  H,  P05  —  02 
for  H2,  and  P05  —  03  for  H3. 

To  this  manner  of  representing  the  generation  of  polybasic 
acids  we  object  that  it  encumbers  the  science  with  numerous 
hypothetical  radicles,  and  that  it  moreover  fails  to  show  the 
actual  successive  generation  of  the  series  of  acids  in  question. 
When  phosphoric  anhydride  is  placed  in  contact  with  water, 
it  combines  with  one  equivalent.  The  union  is  followed  by 
homogeneous  differentiation,  and  two  equivalents  of  metaphos- 
phoric  acid  result.  Two  equivalents  of  this  acid  with  one  of 
water  at  ordinary  temperatures  are  slowly  transformed  into  two 
of  pyrophosphoric  acid,  by  a  reaction  precisely  similar  to  the 
last;  while  two  equivalents  of  pyrophosphoric  acid  when  heated 
with  a  third  equivalent  of  water  yield,  in  like  manner,  two  of 
tribasic  phosphoric  acid.  The  generation  of  the  three  acids 
may  be  represented  as  follows  :  — 

2(P06)  or  (P04)202  +  H202  =  2(P04H)02  or  2(PH06) 
2(PHOa)  or  (PHO5)2O2  +  H2O2  =  2(PH05H)02  or  2(PH,O7) 
2(PH207)  or  (PH206)202  +  H2O2  =  2(PH206H)02  or  2(PH8O8) 

Gerhardt  long  since  maintained  that  we  cannot  distinguish 
between  polybasic  salts  and  what  are  called  sub-salts,  which 


XX.]  THEORY   OF  TYPES  IN   CHEMISTRY.  467 

are  as  truly  neutral  salts  of  a  particular  type.  Thus  the  bibasic 
and  tribasic  phosphates  are  to  be  looked  upon  as  sub-salts, 
which  sustain  the  same  relation  to  the  monobasic  phosphates' 
that  the  basic  nitrates  bear  to  the  neutral  nitrates.  He  suc- 
ceeded in  preparing  two  crystalline  sub-nitrates  of  lead  and 
copper,  having  the  formulas  N05,M202,HO  (tribasic),  and 
IsX^^C^HgOs  (heptabasic),  both  of  which  retain  their  water 
of  composition  at  392°  F. 

The  compounds  of  sulphuric  acid  are  :  1.  The  true  monobasic 
sulphate,  S206MO,  corresponding  to  the  Nordhausen  acid  and 
the  anhydrous  bisulphates ;  2.  The  ordinary  neutral  sulphates, 
S2O6;M202;  3.  The  so-called  disulphates,  S206,M404  corre- 
sponding to  the  glacial  acid  of  density  1.780  ;  4.  The  type 
8206,M606,  represented  by  turpeth  mineral ;  5.  The  so-called 
quadribasic  sulphates,  S206,M808.  The  copper-salt  of  this  octo- 
basic  type  still  retains,  moreover,  6 HO  at  392°  F.  (Gerhardt 
on  Salts,  Jour,  de  Pharmacie,  1848,  Vol.  XII. ;  American 
Journal  of  Science,  VI.  337.)  Without  counting  the  still  more 
basic  sulphates  described  by  Kane  and  Schindler,  we  have  the 
following  salts,  which,  in  accordance  with  Wurtz's  notation, 
correspond  to  the  annexed  radicles  :  — 

1 .  Unibasic  S2HOT     =  SaO6  monatomic. 

2.  Biba-sic  S2HaO8    =  S204  diatomic. 

3.  Quadribasic  S2H4010  =  S202  tetratomic. 

4.  Sexbasic  S2H6O12  =  S2  hexatomic. 

5.  Octobasic  S2H8014   =  S2  —  O2  octatomic. 

It  is  easy  to  apply  a  similar  reductio  ad  absurdum  to  the 
radicle  theory  in  the  case  of  the  oxychlorides  and  other  basic 
salts,  and  to  show  that  the  radicles  of  the  dualists  are  often 
merely  algebraic  expressions.  (See  further  my  remarks  in  the 
American  Journal  of  Science,  VII.  402-404.)* 

*  Those  who  are  familiar  with  chemical  literature  will  remember  an  amus- 
ing ./en  d 'esprit  of  Laurent's,  in  which  he  invited  the  attention  of  the  advo- 
cates of  the  radicle  theory  to  a  newly  invented  electro-negative  radicle, 
eurhizene.  (Comptes  Rendus  <Jes  Travaux  de  Chimie  for  1850,  pages  251 
and  376.)  A  late  writer  in  the  Chemical  News  (Vol.  I.  page  326)  proposes, 
as  a  new  electro-negative  radicle,  tinder  the' name  of  hydrine,  the  peroxide 
of  hydrogen  H0»,  the  eurhizene  of  Laurent. 


468  THEORY  OF    TYPES  IN   CHEMISTRY.  [XX. 

The  mode  of  the  generation  of  acids  set  forth  in  the  case  of 
those  derived  from  phosphoric  anhydride,  which  we  conceive 
to  be  a  simple  statement  of  the  process  as  it  takes  place  in 
nature,  dispenses  alike  with  hypothetical  radicles  and  residues, 
both  of  which  are,  however,  convenient  for  the  purposes  of 
notation.  In  the  selection  of  a  typical  form  to  which  a  great 
number  of  species  may  be  referred,  hydrogen  or  water  merits 
the  preference  from  its  simplicity,  and  from  the  important  part 
which  it  plays  in  the  generation  of  species.  Water  and  car- 
bonic anhydride  are  both  so  directly  concerned  in  the  generation 
of  the  bodies  in  the  carbon  series,  that  either  may  be  assumed 
as  the  type ;  but  we  prefer  to  regard  C204,  like  the  other  an- 
hydrides, as  only  a  derivative  of  the  type  of  water,  and  ulti- 
mately of  the  hydrogen-type. 

These  views  were  first  put  forward  by  myself  in  1848,  when 
I  expressed  the  opinion  that  they  were  destined  to  form  "  the 
basis  of  a  true  natural  system  of  chemical  classification  " ;  and 
it  was  only  after  having  opposed  them  for  four  years  to  those 
of  Gerhardt,  that  this  chemist,  in  June,  1852,  renounced  his 
views,  and,  without  any  acknowledgment,  adopted  my  own. 
(Ann.  de  Chim.  et  Phys.  (3),  XXXVII.  285.)  Already  in 
1851,  "Williamson,  in  a  paper  read  before  the  British  Associa- 
tion, had  developed  the  ideas  on  the  water-type  to  which  Wurtz 
refers  above,  and  to  him  the  English  editor  of  Gmelin's  Hand- 
book ascribes  the  theory.  The  notion  of  condensed  types,  and 
of  H2  as  the  primal  type,  was  not,  so  far  as  I  am  aware,  brought 
forward  by  either  of  these,  and  remained  unnoticed  until  re- 
suscitated by  Wurtz  in  1855,  seven  years  after  I  had  first  an- 
nounced it,  and  one  year  after  my  reclamation  already  noticed, 
which  was  published  in  the  American  Journal  of  Science,  in 
March,  1854. 

My  claims  have  not,  however,  been  overlooked  by  Dr. 
Wolcott  Gibbs.  In  an  essay  on  the  polyacid  bases,  he  re- 
marks that  in  a  previous  paper  he  had  attributed  the  theory 
of  water-types  to  Gerhardt  and  Williamson,  and  adds  :  "  In 
this  I  find  I  have  not  done  justice  to  Mr.  T.  Sterry  Hunt,  to 
whom  is  exclusively  due  the  credit  of  having  first  applied  the 


XX.]  THEORY  OF  TYPES  IN   CHEMISTRY.  469 

theory  to  the  so-called  oxygen-acids  and  to  the  anhydrides,  and 
in  whose  earlier  papers  may  be  found  the  germs  of  most  of  the 
ideas  on  classification  usually  attributed  to  Gerhardt  and  his 
disciples."  (Proc.  Am.  Assoc.  Adv.  Science,  1858,  page  197.) 
It  will  be  seen,  from  what  precedes,  that  I  not  only  applied 
the  theory,  as  Dr.  Gibbs  remarks,  but,  except  so  far  as  Laurent's 
suggestion  goes,  invented  it  and  published  it  in  all  its  details 
some  years  before  it  was  accepted  by  a  single  chemist. 

In  conclusion,  I  have  only  to  ask  that  future  historians  will 
do  justice  to  the  memory  of  Auguste  Laurent,  and  will,  more- 
over, ascribe  to  whom  is  due  the  credit  of  having  given  to  the 
science  a  theory  which  has  exercised  such  an  important  influ- 
ence in  modern  chemical  speculation  and  research  ;  remember- 
ing that  my  own  publications  on  the  subject,  which  cover  the 
whole  ground,  were  some  years  earlier  than  those  of  William- 
son, Gerhardt,  Wurtz,  or  Kolbe. 


470  ON   THE  THEORY  OF  NITRIFICATION.  [XX. 


APPENDIX. 

ON    THE   THEORY    OF    NITRIFICATION. 

IN  connection  with  the  foot-note  on  page  465  the  following  sketch 
of  the  theory  of  nitrification  there  indicated  seems  called  for,  the 
more  especially  as  it  will  be  seen  that  the  late  Professor  G.  C. 
Schaeffer  of  Washington  apparently  anticipated  me  in  certain  points 
therein.  It  was  in  the  Anier.  Jour.  Science  for  May,  1848  (page 
408),  that  I  referred  to  Gerhardt's  observation  that  the  so-called 
protoxide  of  nitrogen  corresponds  to  biphosphamide,  PNO,  and  is 
NNO,  a  nitryl  derived  from  nitrate  of  ammonia  by  the  removal  of 
2H20,  and  capable,  when  heated  in  contact  with  an  alkaline 
hydrate,  of  regenerating  ammonia  and  a  nitrate.  I  then  called 
attention  to  the  similar  decomposition  of  nitrite  of  ammonia, 
which  by  the  loss  of  2H2O  yields  nitrogen  gas,  and  remarked  that 
the  gas  thus  obtained,  "  apparently  identical  with  that  of  the  at- 
mosphere, is  really  composed  of  two  .equivalents  of  the  element  sustain- 
ing to  each  other  the  same  relations  as  in  nitrous  oxide"  or  in  other 
words  representing  respectively  the  nitrous  and  the  ammoniacal 
conditions.  This  view  of  the  constitution  of  gaseous  nitrogen  was 
again  set  forth,  in  September,  1848,  in  the  paper  quoted  above,  as  a 
means  of  explaining  the  apparent  anomaly  in  the  equivalent  volume 
of  nitrogen.  The  obvious  conclusion  that  gaseous  nitrogen  might 
(after  the  manner  of  nitrous  oxide)  regenerate  ammonia  and  a 
nitrite  by  assuming  the  elements  of  water,  2HzO,  was  not  insisted 
upon.  It  was,  however,  for  years  so  familiar  to  me  and  so  often  set 
forth  in  my  lectures  on  chemistry  before  the  medical  classes  at  the 
Universite  Laval  aUQuebec,  that  I  spoke  of  it  in  the  above  paper  in 
March,  1861,  as  a  view  which  I  had  elsewhere  suggested,  though 
this  was,  I  believe,  the  first  time  that  it  had  been  enunciated  by  me 
in  print.  In  further  explanation  of  the  subject  I  published  in  the 
Amer.  Jour.  Science  for  July,  1861  (page  109),  a  note  in  which,  after 
describing  the  generation  of  ozone  or  active  oxygen  by  passing  air 
through  a -solution  of  permanganic  acid,  and  the  production  of  a  ni- 
trite from  air  thus  ozonized,  I  referred  to  the  conversion  of  gaseous 
nitrogen,  as  above,  into  ammonia  and  nitrous  acid,  and  added  : 
"  From  the  instability  of  the  compound  of  these  two  bodies,  however, 
it  becomes  necessary  to  decompose  the  one  at  the  instant  of  its  forma- 


XX.]  ON  THE  THEORY  OF  NITRIFICATION.  471 

tion  in  order  to  isolate  the  other.  Certain  reducing  agents  which 
convert  nitrous  acid  into  ammonia  may  thus  transform  nitrogen  (NN) 
into  2NH$.  In  this  way  I  explain  the  action  of  nascent  hydrogen 
in  forming  ammonia  with  atmospheric  nitrogen  in  presence  of  oxidiz- 
ing metals  and  alkalies An  agent  which,  instead  of  attacking 

the  nitrous  acid,  should  destroy  the  newly  formed  ammonia,  would 
permit  us  to  isolate  the  nitrous  acid.  Houzeau  has  shown  that  ac- 
tive oxygen  is  such  an  agent,  at  once  oxidizing  ammonia  with  forma- 
tion of  nitrate  (nitrite)  of  ammonia  ;  and  thus  when  ozone  is  brought 
in  contact  with  moist  air,  both  of  the  atoms  of  nitrogen  in  the  nitryl 
(NNj  appear  in  the  oxidized  state.  From  this  view  it  follows  that 
the  odor  and  many  of  the  reactions  ascribed  to  ozone  are  due  to 
nitrous  acid,  which  is  liberated  by  the  decomposition  of  atmospheric 
nitrogen  in  presence  of  water  and  nascent  oxygen.  We  have  thus 
the  key  to  a  new  theory  of  nitrification  and  to  the  experiments  of 
Cloez  on  the  slow  formation  of  a  nitrite  by  the  action  of  air  ex- 
empt from  ammonia  upon  porous  bodies  moistened  with  alkaline 
solutions." 

On  September  15,  1862,  I  read  before  the  French  Academy  of 
Sciences  a  note  on  The  Nature  of  Nitrogen  and  the  Theory  of  Nitri- 
fication, published  in  the  Comptes  Rendus  of  that  date  and  trans- 
lated in  the  Philosophical  Magazine  for  January,  1863,  in  which  I 
repeated  the  points  above  given,  and  then  proceeded  to  consider  the 
results  announced  by  Schb'nbein  in  1862.  I  said  :  "  The  formation  of 
nitrite  of  ammonia  by  the  combination  of  the  nitryl  NN  with 
H40,  must  necessarily  be  limited  to  very  minute  quantities  by  the 
instability  of  this  ammoniacal  salt,  which,  as  is  well  known,  decom- 
poses readily  into  nitrogen  and  water.  In  order,  therefore,  to  pro- 
duce any  considerable  quantity  of  a  nitrite  by  this  reaction,  there  is 
required  the  presence  of  active  oxygen,  or  of  a  fixed  base  to  separate 
the  ammonia.  The  recent  experiments  of  Schonbein  have  furnished 
new  evidences  of  the  direct  formation  of  a  nitrite  at  the  expense  of 
the  nitrogen  of  the  atmosphere.  According  to  him,  when  sheets  of 
paper  moistened  with  a  feeble  solution  of  an  alkali  or  an  alkaline 
carbonate  are  exposed  to  the  air,  especially  in  the  presence  of  watery 
vapor  and  at  a  temperature  of  50°  or  60°  C.,  the  alkaline  base  soon 
fixes  a  sufficient  quantity  of  nitrous  acid  to  give  the  characteristic 
reactions.  Appreciable  traces  of  nitrite  are,  according  to  Schonbein, 
obtained  in  this  way,  even  without  the  intervention  of  an  alkali. 
He  moreover  found  that  distilled  water  mixed  with  a  little  potash 
or  sulphuric  acid,  and  evaporated  slowly  at  a  temperature  of  about 


472  ON  THE  THEORY  OF  NITRIFICATION.  [XX. 

50°  C.,  in  the  open  air,  fixes  in  one  case  a  small  portion  of  ammonia 
and  in  the  other  a  little  nitrous  acid.  Traces  of  a  nitrite  are  also 
formed  in  pure  water  under  similar  conditions.  Schonbein  explains 
all  of  these  results  by  the  combination  of  nitrogen  with  the  elements 
of  the  water,  producing  at  the  same  time  ammonia  and  nitrous  acid. 
As  he  has  well  remarked,  this  reaction  serves  to  explain  the  absorp- 
tion of  nitrogen  by  vegetation,  and,  through  the  oxidation  of  nitrites, 
the  formation  of  nitrates  in  nature.  By  these  elegant  experiments 
he  has  confirmed  in  a  remarkable  manner  my  theory  of  nitrification 
and  of  the  double  nature  of  free  nitrogen.  It  is,  however,  evident 
that  since  the  publication  of  my  note  of  March,  1861,  above  referred 
to,  we  cannot  say,  with  Schonbein,  that  the  generation  of  nitrite  of 
ammonia  from  nitrogen  and  water  is  *  a  most  wonderful  and  wholly 
unexpected  thing.'  (Letter  from  Schonbein  to  Faraday,  Philos. 
Magazine,  June,  1862,  page  467.)  "  Keferring  to  the  claims  of  Schon- 
bein, and  to  my  notes  of  March  and  July,  1861,  the  late  Professor 
Nickles  wrote  as  follows  in  1863,  in  his  scientific  correspondence  for 
the  American  Journal  of  Science  ((2)  XXXV.  263)  :  "  Schonbein 
has  done  justice  tardily  to  those  who  have  preceded  him  in  this 
question.  Of  this  number  is  T.  Sterry  Hunt,  who,  as  our  readers 
may  remember,  long  since  showed  that  nitrite  of  ammonia  may  be 
formed  by  means  of  nitrogen  and  water,  and  thus  led  the  way  to  a 
new  theory  of  nitrification.  This  is  what  Bottger  arrived  at,  who 
first  announced  that  nitrite  of  ammonia  is  a  product  of  all  combus- 
tion in  the  air."  With  regard  to  the  production  of  nitrite  of  am- 
monia from  nitrogen  and  water,  he  further  adds,  "  this  point  was 
entirely  developed  by  Sterry  Hunt." 

The  publication  of  the  above  called  forth  a  communication  from 
Professor  G.  C.  Schaeffer  in  the  Amer.  Jour.  Science  for  November, 
1863,  page  409,  in  which  he  draws  attention  to  the  fact  that  the  Ee- 
port  of  the  Smithsonian  Institution  for  1861  contains  an  essay  on 
Nitrification  by  Dr.  B.  F.  Craig  (written  in  1856),  in  which  the  lat- 
ter puts  forth  as  the  suggestion  of  Professor  Schaeffer  the  same 
theory  of  nitrification  as  that  maintained  by  the  present  writer  and 
by  Schonbein  ;  basing  it  upon  the  view  that  nitrogen  gas  is  a  nitryl 
capable  of  regenerating  nitrite  of  ammonia  in  presence  of  water. 
From  this  it  is  clear  that  Professor  Schaeffer  had  independently  at- 
tained the  same  conclusion  as  myself  from  the  conception  of  the 
dual  nature  of  atmospheric  nitrogen,  which  I  had  taught  since  1848. 
He  at  the  same  time,  as  a  contribution  to  the  literature  of  the  subject, 
called  attention  to  his  paper  in  the  Proceedings  of  the  American  As- 


XX.]  ON  THE  THEORY  OF  NITRIFICATION.  473 

sociation  for  the  Advancement  of  Science  for  1850,  on  the  Detection 
of  Nitrites  and  Nitrates,  in  which  he  indicated  a  delicate  test  for 
these  salts,  showed  the  frequent  presence  of  nitrites  in  rain-water, 
and  moreover  pointed  out  that  while  nitrates  are  readily  reduced  to 
nitrites  in  solution,  these,  by  oxidation,  pass  as  readily  into  nitrates. 


INDEX. 


ACCUMULATION  of  sediments,  effects 

of,  17,  49,  58,  66. 
Acid  springs,  111 ;  of  New  York  and 

Ontario,  130,  131. 
Acids  of  volcanoes,  their  origin,  8,  15, 

111,  112. 

Adams,  C.  B.,  on  the  geology  of  Ver- 
mont, 391. 
Adirondack  Mountains,  rocks  of,  32, 

241,  243. 

Aerolites,  constitution  of,  302. 
Agalmatolite  rocks,  67. 
Albertite,  composition  of,  176. 
Albite,  in  Laurentian  veins,  214; 

mula  of,  443. 
Albuminoids,    constitution    and    arti 

ficial  production  of,  170. 
Algae.     See  Sea-weeds. 
Alkalies,  relative  proportions  in  waters, 

102;   of  mineral  waters,    135. 

Carbonate  of  Soda  and  Potash. 
Alkaliferous    silicates,    decomposition 

of,  2,  10,  40,  102,  103. 
Alkaline  silicates,  soluble,  7,  21,  25. 
Alkaline  waters,  85,  123,  156. 
Alleghany  River,  brines  of,  121. 
Allomerism,  447. 

Alps,  geology  of,  328;  anthracitic  sys- 
tem   of,    332  ;     grand    section    of, 

343. 
Alteration   of  rocks.     See  Metamor- 

phism. 

Alum  slates  of  Sweden,  266,  366. 
Alumina,  solution  and  deposition  of, 

13,  14,  98,  142;  sulphate  of,  98,  133 

in  waters,  142.     See  Bauxite. 
Aluminous  silicates,  origin  of,  28,  296, 

298. 
Ammonia  of  volcanoes,   8,  15,   113; 


in  rocks  and  soils,  113;  nitrite  of,  its 
production,  471. 

Andalusite  rocks,  28,  32,  34,  243,  272, 
282,  408. 

Andrews,  E.  B.,  on  petroleum,  174. 

A.ngelin,  Palaeontologica  Scandinavica, 
367. 

Anglesea,   crystalline  schists  of,  270, 
353,  383. 

Anhydrites  of  the  Alps,  335. 

Anhydrous  monobasic  acids,  464. 

Anorthite,  its  formula,  443. 

Anortholite,  31,  32. 

for-  Anthracite,  its  origin,  177 ;  of  the  Alps, 
332,  334. 

Anticlinals,  their  relations  to  moun- 
tains, 53. 

Anticosti,  geology  of,  416. 

Anticosti  group,  417. 
See  Apatite,  197,  208,  211,  213,  811. 

Appalachians,  geology  of,  50,  51,  75, 
241. 

Aquatic  vegetation,  2,  22,  95. 

Arendal,  vein-stones  of,  209. 

Arenig  rocks,  375,  376,  381,  384. 

Arkesine,  330. 

Arkose,  285. 

Artesian  wells  of  London  and  Paris, 
85. 

Aspidella  Terranovica,  410. 

Atmosphere,  primeval,  1, 20, 40,  42,  47, 
301. 

Atmospheric  waters,  94. 

Atomic  hypothesis,  433,  438. 

Atomic  volumes,  433,  435,  440,  455. 

Attrition  of  rocks,  20. 

Auroral  rocks,  247,   421;  their  rela- 
tion to  matinal,  414. 

Azoic  gneisses  of  Rogers,  246. 


476 


INDEX. 


BABBAGE  on  internal  heat,  14,  71. 

Bala  rocks,  353,  359,  362. 

Bailey,  L.  W.,  geology  of  New  Bruns- 
wick, 407. 

Banded  structure  in  veins,  193,  199. 

Bangor  group,  353,  382,  384. 

Bark,  its  composition,  181. 

Barrande  on  palaeozoic  geology,  253, 
368,  369,  378*  392,  424. 

Baryta,  salts  of,  in  waters,  87, 121, 141, 
145. 

Basic  salts,  Gerhardt  on,  467. 

Bauxite,  14,  98,  326. 

Beloeil,  Quebec,  water  of,  151. 

Belt,  TM  on  Lingula  flags,  371. 

Bergmann  on  Mont  Blanc,  338. 

Bertrand  on  Mont  Blanc,  338. 

Berzelius  on  silicate  of  lime,  151. 

Beryl,  199,  245;  kaolin  of,  101;  a 
feldspathide,  445. 

Bessarabia,  salt  lagoons  of,  86. 

Bicarbonates.     See  Carbonates. 

Biddeford,  Maine,  granitic  veins  of,  198. 

Bigsby,  J.,  on  Huronian  rocks,  18, 
269 ;  on  Cambrian,  269 ;  on  the  geol- 
ogy of  Quebec,  396,  400. 

Billings,  E.,  on  the  geology  of 
mont,  260-265,  391-393;  on  the 
Potsdam  rocks,  266;  on  Levis  fos- 
sils, 258,  400,  403,  404,  412  ;  on 
Eophyton,  409  ;  on  the  Anticosti 
group,  416;  on  Middle  Silurian,  417. 

Bischof,  G.,  16;  on  a  source  of  sulphu- 
retted hydrogen,  87;  on  decomposi 
tion  of  silicates,  102, 151 ;  on  formation 
of  silicate  of  magnesia,  122;  on 
anthracite.  177;  on  deoxidation  in 
nature,  302 ;  on  pseudomorphism,  287. 
290,  293,  294,  323,  325 ;  his  plutonic 
basis,  294. 

Bismuth,  occurrence  of,  200,  217. 

Bitterns  related  to  mineral  waters, 
103,  105,  109,  114,  117,  121, 156,  163. 

Bitumens,  8,  169,  175,  382,  397.  See 
Petroleum. 

Bituminous  rocks.     See  Pyroschists. 

Blake,  W.  P.,  on  Laurentian  veins, 
215,  218. 

Blue  Ridge,  gneisses  of,  217,  249;  their 
decomposition,  250;  their  copper 
veins,  217,  250. 


Blum  on  pseudomorphism,  287,  319, 

325. 
Bohemia,  copper  slates  of,  232 ;  geology 

of,  368. 

Borates,  their  origin,  16,  112,  146. 
Borax-lake,  water  of,  146. 
Bosanquet,  Ontario,  pyroschists  of,  179. 
Bothwell,  Ontario,  water  of,  159,  162. 
Bottger  on  nitrification,  472. 
Boue  on  metamorphism,  24,  321. 
Brainard,  J.,  on  silicious  deposits,  89. 
Braintree,  Mass.,  Paradoxides  of,  405. 
Bray  Head,  rocks  of,  382. 
Brazil,  crystalline  rocks  of,  278;  their 

decay,  10. 
Breaks  in  palasozoic  series,  263,  375  - 

377,  412-415,  418. 
Breislak  on  the  origin  of  sulphur,  87. 
Brines,  analyses  of,  119  - 121. 
Brittany,  crystalline  schists  of,  273. 
Bromine  in  waters,  142. 
Brooks,   T.    B.,    crystalline    rocks    of 

Michigan,  274. 
Brunswick,   Maine,  granite  veins  of, 

194. 

Buch,  Von,  on  dolomites,  81,  309. 
Ver-  Buffon  on  mountains,  52. 

Bunsen  on  eruptive  rocks,  3,  66,  284  ; 

on  aqueous  decomposition  of  silicates, 

102. 

CAERNARVONSHIRE,  crystalline  rocks 
of,  269,  353,  383. 

Calciferous  sand-rock,  a  dolomite,  117, 
155,  415;  gypsum  in,  117, 155;  its  re- 
lations to  Trenton  and  Chazy,  412, 
413. 

Cagniard  de  la  Tour  on  vapors,  37. 

Calcium,  chloride  of,  in  waters,  117- 
120,  158. 

Calcium,  salts  of.  See  Carbonate  of 
lime,  Lime-salts,  and  Gypsum. 

Caledonia,  Ontario,  waters  of,  123, 127, 
129,  147-149. 

California,  borax-lake  of,  146. 

Calumet  and  Hecla  mine,  conglomerate 
of,  187. 

Cambrian  series,  266-269;  Upper,  in 
Great  Britain,  350  -  365  ;  Middle  and 
Lower,  365-385,  409;  in  North 
America,  387  -  425;  history  of,  349. 


INDEX. 


477 


Cambro-Silurian  of  Sedgwick,  363, 381, 
423. 

Canada  geological  survey,  reports  of, 
420. 

Cape  Ann,  Mass.,  granite  veins  of,  200. 

Cape  Breton,  water  of,  121. 

Caradoc  rocks,  353,  359  -  362,  384. 

Carbon,  its  primitive  condition,  23,  42, 
302 ;  anthracitic  of  Madoc,  217. 

Carbonates.  See  Carbonate  of  lime, 
Carbonate  of  magnesia,  Carbonate 
of  soda,  and  Carbonic  acid. 

Carbonate  of  lime,  its  origin,  2,  23, 
41,  47,  81,  83,  86,  88,  90,  109;  solu- 
bility and  supersaturated 
of,  139;  bicarbonate,  its  action  on 
sea-water,  82,  85,  90,  109,  308;  hy- 
drous carbonate  of,  140. 

Carbonate  of  lime  and  magnesia. 
Dolomite. 

Carbonate  of  magnesia,  its  origin,  23, 
82,  85,  88,  90,  109,  110;  action  of,  on 
lime-salts,  87,  90,  139;  its  solubility 
and  supersaturated  solutions  of,  140, 
148;  bicarbonate  of,  its  solubility,  91, 
109,  148 ;  hydrous  carbonate  of,  pres- 
ent in  some  dolomites,  107;  sesqui- 
carbonate  of,  138. 

Carbonate  of  soda,  its  origin,  12,  21, 
85,  102;  amount  of,  in  waters,  85, 
124-126;  neutral  carbonate  of,  148; 
action  of,  on  sea-waters,  2, 11, 12,  41, 
85,  88,  90,  105,  139,  148,  307. 

Carbonic  acid,  its  action  on  silicates, 
2,  10,  102,  150;  amount  of,  in  early 
atmosphere,    41,  47,   308;  deoxida- 
tion  of,  23,  42,  302 ;  deficiency  of,  in 
certain  waters,  149;  relations  of, 
life  and  climate,  42,  46-48;  to 
formation  of  gypsum,  42,  308;  su 
terranean  sources  of,  8,  15,  112. 

Carboniferous  rocks,  228;  of  North 
America,  49,  50. 

Carbon-spars,  their  constitution,  441, 
446. 

Carlsbad,  waters  of,  85. 

Carnallite,  105,  107, 118. 

Cassiterite,  191,  192,  195,  200,  205; 
pseudomorphs  of,  289,  290. 

Catalysis,  452. 

Celestial  chemistry,  35,  37. 


Chabazite,  442;  action  of  saline  waters 
on,  96. 

Chacornac  on  the  nebular  hypothesis, 
38. 

Chambly,  waters  of,  125, 149,  152. 

Champlain  division,  252,  258,  264,  266. 

Chamonix,  Jurassic  rocks  of,  338; 
synclinal  of,  343. 

Chatham,  Ontario,  water  of,  145. 

Chazy  formation,  156,  414,  415 ;  absent 
hi  Herkimer  Co.,  New  York,  413; 
relations  of,  to  Calciferous  and  Tren- 
ton, 412;  mineral  waters  from,  124, 
156, 157. 

solutions  Chemical    change    defined,   428,   450, 
454,  465;  elements,  37,  428;  activi- 
ties in  former  ages,  27,  42,  306 ;  dis- 
sociation, 36. 
See  Chemistry  defined,  454. 

Cheshire  rock-salt,  120. 

Chiastolite  rocks.     See  Andalusite. 

Chicago,  oil-bearing  limestone  of,  172. 

Chloride  of  calcium  in  waters,  122, 158; 
in  primeval  ocean,  11,  117,  122,  137. 

Chloride  of  magnesium,  117,  122,  137. 

Chloride  of  sodium,  its  origin,  2, 11, 41. 

Chlorine  in  silicates,  144,  242. 

Chlorine  and  hydrogen,  union  of,  430. 

Chlorite,  its  probable  origin,  296. 

Chloritic  rocks,  32,  243,  247,  249,  269, 
270,  330,  331,  408:  supposed  pseudo- 
morphic  origin  of,  316,  320,  326. 

Chloritoid  rocks,  32. 

Chromium,  its  occurrence,  31,  32,  34, 
238,  243,  249,  269,  270,  272,  297,  330. 

Chrysolite  and  serpentine,  291,  315. 

Chrysoberyl,  195,  214. 
to  Circulation,  terrestrial,  22,  225,  235. 
the  Classification  of  the  sciences,  35,  453. 
b-  Clays,  origin  of,  2,  10,  13,  20,  22,  41, 
101,228;  precipitated  by  saline  wa- 
ters, 10. 

Climate,  primeval,  42,  46  -  48 ;  palaeo- 
zoic of  North  America,  76,  92,  310. 

Cloez  on  nitrification,  465,  471. 

Coal,  its  origin,  180,  182,  229;  its  rela- 
tion to  iron-ores,  229. 

Collingwood,  Ontario,  pyroschists  of, 
178. 

Colloidal  bodies,  solution  of,  223. 

Condensed  types  in  chemistry,  468. 


478 


INDEX. 


Concentration  of  metals  in  nature,  227, 
235. 

Concretionary  structure,  89. 

Connecticut,  gneisses  of,  248. 

Conocephalites  in  North  America,  260, 
391,  404. 

Continent,  a  pre-palaeozoic,  75,  76. 

Continental  elevation,  53,  76. 

Conularia,  a  phosphatic  shell,  312. 

Cooke,  J.  P.,  on  allomerism,  447. 

Cooling  globe,  its  chemistry,  1,  38,  40, 
60,  63,  301,  306. 

Coos  group,  282. 

Copper-ores,  origin  of,  232;  of  Blue 
Ridge,  217. 

Coprolites,  152,  225. 

Cordier  on  limestones  and  dolomites,  81. 

Corundum,  247;  its  supposed  trans- 
formations, 326. 

Cotta,  Von,  on  granitic  veins,  191. 

Credner,  H.,  on  Eozoic  rocks  of  North 
America,  277;  on  comparative  geog- 
nosy, 278;  on  the  origin  of  silicates, 
304^  305. 

Crinoids,  fossil,  injected  with  silicates, 
304. 

Croft,  H.,  on  various  mineral  waters, 
130,  134,  145. 

Crust  of  the  earth,  1,  40,  60-64,  223 
its  flexibility,  8,  15.  57,  72;  corruga- 
tions of,  57,  74;  its  disintegration,  63. 

Crystalline  aggregation  of  matter,  305. 

Crystalline  rocks,  two  great  classes, 
283;  evidences  of  their  plasticity, 
4;  how  formed,  24,  283;  evidences  of 
life  in,  13,  302. 

Crystalline  schists,  relative  ages  of, 
19;  are  pre-Cambrian,  327;  origin 
of,  283;  supposed  plutonic,  294; 
Daubr<*e  on,  301;  Giimbel  on,  305; 
Credner  on,  305;  Favre  on,  347. 

Crystals,  rounded,  212;  hollow  or 
skeleton,  201,  212. 

Cumberland,  England,  crystalline 
schists  of,  273. 

Cyanite  rocks,  28,  34,  243,  272. 

Cycles  in  sedimentation,  155,  241. 


DALMAN  on  trilobites,  365. 
Damour,  A.,  action  of  water  on 
lites,  102;  on  jadeite,  446. 


Dana,  J.  D.,  on  the  fluidity  of  the 
earth's  interior,  56;  on  granite  veins, 
199;  on  pseudomorphism,  287,  291, 
318,  319,  320-323;  on  regional  met- 
amorphism,  291,  320,  322 ;  on  equiv- 
alent volumes,  433. 

Danville,  Maine,  granite  veins  of,  197. 

Daubeny  on  volcanoes,  62. 

Daubree  on  the  action  of  heated  wa- 
ters, 6;  on  the  attrition  of  rocks.  20; 
on  the  waters  of  Plombieres,  25;  on 
the  production  of  silicates,  25,  297; 
on  silicious  deposits,  89;  on  regen- 
eration of  feldspar,  100;  on  granitic 
veins,  191,  209;  on  the  origin  of 
crystalline  schists,  301;  on  the  pri- 
meval atmosphere,  301. 

Davy,  H.,  on  volcanoes,  62. 

Dawson,  J.  W.,  on  dissolving  of  iron- 
oxide  from  sediments,  13  ;  on  the 
origin  of  coal,  180-182;  on  Eozoon 
Canadense,  302  ;  on  palagozoic  for- 
aminifera,  411  ;  on  the  geology  of 
Nova  Scotia,  408;  on  Erian  rocks, 
419;  on  Cambrian  and  Silurian,  424. 

Dead  Sea,  water  of,  83. 

Decomposition,  double,  in  chemistry, 
428,  451. 

Decomposition  of  crystalline  rocks,  its 
antiquity,  10,  100,' 250. 

Delabeche  on  crystalline  rocks,  301. 

Delesse,  A.,  on  envelopment  of  min- 
erals, 288,  289,  314,  315;  on  pseudo- 
morphism, 292,  314-318;  his  change 
of  views,  316;  on  the  origin  of  ser- 
pentine, 316,  317 ;  on  protogine,  330. 

Deoxidation  in  nature,  23,  230,  302. 

Deville,  H.  Ste.-Claire,  on  dissociation, 
37;  on  river-waters,  84;  on  crystal- 
line aggregation,  305. 

Diabase,  31. 

Diagenesis  in  rocks,  305,  317,  321. 

Differentiation,  chemical,  450. 

Dikes,  distinguished  from  veins,  193, 
202. 

Diorite,  23,  26,  32,  186,  243,  247,  249, 
269,  270,  330,  331,  408. 

Disintegration  of  the  primitive   crust, 


zeo-  Dissociation,  chemical,  37. 
Dipyre,  446. 


INDEX. 


479 


Dolerite,  3,  23,  284;  stratiform  strnc-l    rocks,  5,  190;  on  silicious  deposits, 
tare  in,  186.  89,  on  granitic  veins,  189;  on  ter- 

Dolomieu,  decay  of  granite,  10.  restrial  circulation,  226 ;   on  Alpine 

Dolomite,  origin  of,  81,  307 ;  two  classes     geology,  332,  348. 
of,  with  and  without  gypsum,  87,  88, 'Emerald  veins  of  New  Grenada,  205. 
309;  fresh-water,  88;   metalliferous,  Emery,  origin  and  occurrence  of,  13, 
88,  309 ;  is  not  decomposed  by  gyp-     98. 

sum,  106;  with  hydrate  and  hydro-  Emmons,  E.,  on  rounded  crystals,  212; 

on  eruptive  limestone?,  218;  on  the 
Green  Mountains,  250;  on  serpen- 
tine, 250;  on  the  Taconic  system, 
251-253,  268,  388-390;  on*  Cam- 
brian, 268;  on  hypersthene  rock, 


carbonate  of  magnesia.  107;  organic 
remains  in,  88,  92;  artificial  forma- 
tion of,  90,  91,  307;  produced  by 
evaporation  in  closed  basins,  76,  85- 
88,  92,  101,  310;  relations  of  car- 
bonic acid  in  the  atmosphere  to  its 
formation,  43,  308 ;  supposed  epigenic 


279;  on  recomposed  rocks,  341;  on 
the  geology  of  New  York,  368. 

origin  of,  81,  92,  287,  307,  325;  Cor-  Endogenous  rocks,  193,  196-199. 

dier  on,  81;   Von  Morlot  and  Marig-|  Envelopment    of  minerals,  288-290, 

nac  on,  308 ;   Von  Buch  on,  81,  309 ; 


Haidinger  on,  325. 


314. 
Eophyton,  385,  409. 


Donegal,  Ireland,  crystalline  rocks  of,  Eozoic  rocks  of  North  America,  75, 

34,-  272.  277. 

Drops,  Guthrie  on,  10.  Eozoon  Canadense,  302,  303,  326,  342, 


Dualism  in  chemical  theory,  428. 
Dublin,  Ireland,  granite  veins  of,  199. 
Ducktown,  Tenn.,  copper  veins  of,  217, 

250. 

Dumas  on  chemical  types,  462. 
Dumont  on  disturbed  strata,  334. 
Durocher  on  igneous  rocks,  3,  189, 190. 
Dynamical  geology,   some   points  in, 

70. 

EARTH,  compared  to  an  organism,  236; 
interior  of,  whether  liquid  or  solid, 


7,  16,  39,  44, 56,  59,  60,  70,  71 ;  its  re-  Eruptive  rocks.     See  Exotic  rocks. 


lation  to  magnetism,  60.     See  Crust 

of  the  earth. 
Eaton,  Amos,  classification  of  rocks, 

241;  on  the  rocks  of  Vermont,  241, 

252. 
Ebelman,  decay  of  silicious  minerals, 

100. 
Eichhorn,  action  of  saline  waters  on 

soils  and  aluminous  double  silicates, 

95,  96. 

Elaeolite  in  granitic  veins,  200. 
Elements,    chemical,   distribution    of, 

221;  in  other  worlds,   36;  possible 

new  ones  in  stars,  37. 
Elevation  of  continents,  15, 17,  53,  76. 


Elie  de  Beaumont  on  water  in  igneous  Fariolo,  Italy,  granites  of,  201. 


411;  E.  Bavaricum,  368. 

Epidermal  tissues,  their  relations  to 
coal,  181. 

Epidotic  rocks,  32,  243,  249,  408. 

Epigenesis,  286,  313,  317. 

Equilibrium  of  pressure,  15,  76. 

Equivalent  volumes,  433,  436,  440. 

Equivalent  weights  of  oxygen  and  car- 
bon, 176;  of  compound  species,  432, 
441;  defined,  455. 

Erian  rocks,  419. 

Erosion  as  related  to  mountains,  52,  74. 


Esmark  on  norites,  279. 

Essex  County,  New  York,  norites  of, 
279. 

Euphotide,  330,  334,  445. 

Eurhizene  of  Laurent,  467. 

Evans  on  petroleum,  174. 

Exotic  rocks,  4,  9,  16,  24,  44,  58,  66, 
188-190,  284;  banded  structure  in, 
186;  local  alteration  by,  298. 

FAHLERZ,  217. 

Fairbairn  on  relations  of  pressure  to 

fusion,  39. 
Fan-like  structure  of  the  Alps,  342, 

343. 


480 


INDEX. 


Faults  in    strata,  related    to  mineral 

springs,  154,  157. 
Favre,  Alph.,   on  the  geology  of 

Alps,  328 ;  on  metamorphism  in  the 

Alps,  342,  347. 
Favre  and  Silbermann,  thermo-chemi- 

cal  researches,  436. 
Faye,  constitution  of  the  sun,  37. 
Feldspar-porphyries,  187,  243,  250,  282. 
Feldspars,  their  formation,  6,  25,  27, 

100 ;  decay  of,  101 ;  triclinic,  31,  67, 

279,  443;  aqueous  origin  of,  298,299; 

constitution  and  formulas  of,  443. 
Feldspathides,  445. 
Festiniog  group,  353,  371,  379,  384. 
Fire-clays,  13,  22,  228. 
Fissures,  veins  in,  202,  203,  233. 
Fitzroy,  water  of,  124,  142,  152. 
Flora,  fossil  of  the  Alps,  333. 
Fluid-cavities  in  crystals,  65,  205. 
Flysch  of  the  Alps,  337. 
Foldings  in  strata,  17,  51,  55-57,  74. 
Fontainebleau  sandstone,  289. 
Foraminifera,  palaeozoic,  411. 
Forchhammer  on  fucoids^  96 ;  on  alka- 
line sulphurets,  99. 

Ford,  geology  of  Troy,  New  York,  407. 
Formulas  in  chemistry,  465. 
Foucou  on  native  hydrocarbon  gases, 

182. 
Fouque*  on  native  hydrocarbon  gases, 

182. 
Fournet    on     kaolinization,    100;    on 

granites,  190;  on  skeleton  crystals, 

201 ;  on  veins,  202. 
Fucoids,  geological  relations  of,  2,  22, 

96,  144,  226. 
Fusion,  when  affected  by  pressure,  65, 


GARNET  rock,  30. 

Gaspe",  geology  of,  406,  415,  418. 

Gas  springs,  hydrocarbon,  8,  112,  131, 

182. 

Gastaldi,  geology  of  the  Alps,  347. 
Gay-Lussnc,  law  of  volumes,  438. 
Gelatine,  formula  and  constitution  of, 

180. 
Generation  of  chemical  species,  427, 

465. 
Genesee  slates,  pyroschists,  178. 


the  Geognosy, 


Genth,  F.  A.,  on  gold  deposits,  237;  on 
corundum,  326 

,240;    comparative,  33,   34, 
278. 

Geological  relations  of  mineral  waters, 
154,  156. 

Geology,  its  scope  and  objects,  239. 

Georgia,  Vermont,  fossils  of,  391,  394, 
402. 

Gerhardt  on  types  in  chemistry,  462, 
468 ;  on  basic  salts,  467. 

Gibbs,  Wolcott,  on  the  water-type  in 
chemistry,  468. 

Giekie  on  the  geology  of  Skye,  281; 
on  Cambrian  and  Silurian,  424. 

Glaciation  of  rocks,  10. 

Glass  softened  by  heated  water,  6. 

Glauconite,  relation  of  to  potash,  2, 
13,  136 ;  in  organic  forms,  303. 

Glucose  and  sea-salt,  compound  of,  441. 

Gneiss  denned,  188 ;  granitoid,  185, 
188,  206,  243;  Laurentian,  206,  243  ; 
White  Mountain,  188,  244,  282;  of 
the  Appalachians,  244  -  250;  of  Nova 
Scotia,  408  ;  primitive  of  Scandi- 
navia, 469. 

Goderich,  salt-wells  of,  204. 

Goethe,  287. 

Gold,  in  Madoc,  Ontario,  217;  its  solu- 
tion and  deposition  in  nature,  232, 
237;  in  sea-water,  237,  238;  of  North 
Wales,  383 ;  of  Nova  Scotia,  408. 

Gothland,  geology  of,  366. 

Granite,  decay  of,  10;  not  a  primitive 
rock,  43;  substratum  of,  unknown, 
33,  43;  intervention  of  water  in  its 
formation,  5,  65,  189-191;  defined, 
183;  an  intrusive  rock,  33,  183;  strat- 
iform structure  in,  186 ;  graphic, 
195 ;  its  origin.  See  Exotic  rocks. 

Granites  of  New  England,  186,  188;  of 
New  Brunswick  and  Italy,  201;  of 
the  Alps,  331. 

Granitic  vein-stones,  183,  189  -  209  ; 
their  aqueous  and  concretionary  ori- 
gin, 33,  192,  199;  banded  structure 
of,  198  ;  mineralogy  of,  200,  210; 
Laurentian,  33,  208;  of  White 
Mountain  series,  194;  of  Sherbrooke, 
Nova  Scotia,  and  of  Biddeford,  Maine, 
198. 


INDEX. 


481 


Graphite,  its  probable  organic  origin, 

13,  301;   in  Laurentian  veins,  210, 

216;  in  various  rocks,  32,  33,243- 

245,  248;  in  aerolites,  301. 
Graptolites  of  the  Levis  formation,  258, 

396,  399,  412. 

Gras  on  Alpine  geology,  332. 
Graywacke  defined,  350;  of  Quebec, 

396,  397,  401 
Green  Mountain  rocks,  18,  29,  32,  241, 

243,  249,  274. 
Grenatides,  445. 
Grenville,  Quebec,  minerals  of,  215; 

section  of  Chazy  at,  414. 
Groton,  Connecticut,  granite  of,  186. 
Grove  on  dissociation,  37. 
Grttner  on  filling  of  veins,  203. 
Guano  deposits,  225. 
Guelph  formation,  417. 
Giimbel  on  Eozoon,  303,  304;  on  meta- 


genesis, 305,  321 

Guthrie  on  drops,  10. 

Gypsum,  origin  of,  43,  86,  90;  two 
modes  of  formation  of,  110;  from  bi- 
carbonate of  lime  and  sulphate  of 


duction,  43,  308 ;  its  action  on  soils, 
97;  does  not  decompose  dolomite, 
106 ;  is  decomposed  by  hydrous  car- 
bonate of  magnesia,  107;  its  solu- 
bility in  water,  insolubility  in  brines, 


Hallowell,  Ontario,  water  of,  116,  142. 

Halysites  in  the  Trenton  limestone,  417. 

Harlech  rocks,  372,  373,  377,  382. 

Hartt,  C.  F.,  on  the  geology  of  Brazil, 
278;  of  New  Brunswick,  406. 

Hastings  County,  Ontario,  rocks  of, 
216,  274. 

Haughton  on  the  norites  of  Skye,  281. 

Heat,  internal,  of  the  earth,  7,  9, 15,  43, 
57,  59  -  66,  71,  72,  77,  78. 

Heer,  0.,  fossil  flora  of  the  Alps,  333. 

Hegel  on  the  "chemical  process,  450. 

Helderberg.       See  Lower  Helderberg. 

Hennessey  on  the  earth's  crust,  7,  16. 

Herkimer  County,  New  York,  geology 
of,  413. 

Herschel,  J.  F.  W.,  on  volcanic  phenom- 
ena, 8,  15,  44,  62. 

Hicks  on  Cambrian  geologv,  372,  373, 
375,  384,  409. 


morphism  of  rocks,  305;    on  dia-  Hisinger,  geology  of  Scandinavia,  366 ; 


errors  in  his  works,  258,  366,  395. 
Hitchcock,  C.  H.,  geology  of  the  White 

Mountains,  282. 
Hoboken,  New  Jersey,  serpentines  of, 

248. 


magnesia,  82,  85-  87,  90,  109;  inter-  Hoffmann  on  Eozoon,  303. 

vention  of  carbonic  acid  in  its  pro-  Homologous  or  progressive   series  in 


chemistry,  431,  439,  442. 
Hoosic  Mountain,  Emmons  on,  250. 
Hopkins  on  the  earth's  ulterior,  7,  16, 

44,  60,  64. 
Hornblende,  its  decay,  100 ;  association 

of,  with  pyroxene,  215 ;  rocks  of,  244, 

246.     See  Diorites. 


83,  85,  91,  107-110, 144;  occurrence 

of,  in  natural  waters,  105,  132  ;  its 

elimination  from,  by  reduction,  99,  Houzeau  on  ozone,  471. 

145;  of  fresh-water  origin,  87;  in  Gal-1  How  on  mineral  waters,  121. 

ciferous  sand-rock,  117, 155;  in  Onon-'Hudson  River  group,  252, 256,  258, 395, 

daga  formation,  132  ;  in  crystalline!    397,  398,  402,  403;  mineral  waters 

schists  in  Sweden,  336;   in  tertiary!     from,  116,  124,  156. 

in  the  Alps,  345.    See  Anhydrite.      jHuggins,  his  spectroscopic  studies,  85. 

|Humboldt  on  granites,  190. 
HAIDINGER  on  pseudomorphism,  324.    Huronian  rocks,  18,  29,  243,  269,  272, 


Hall,  James,  on  sources  of  palaeozoic 
sediment,    49;    on    mountains,    51, 


274;    their   identity  with  the  Urs- 
cheifer,  269.     See  Green  Mountain 


63  -  55,  73 ;  on  White  Mountain  rocks,      series. 

271;  on  Potsdam  rocks,  389;  on  New; Button  on  metamorphism,  24;  on  pri- 

York   geology,    387,   389,   404 ;    on     mary  schists,  338. 

rocks  of  Georgia,  Vermont,  402;  on  Hydrocarbon  gases,  8,  112,  131,  182. 

Taconic  fossils,   392;  on  American 'Hydrochloric  acid,  its  volcanic  origin, 

palaeozic  nomenclature,  419.  '    8,  15,  44;  in  mineral  waters,  111. 


482 


INDEX. 


Hypersthene  rock  or  hyperite,  29,  31, 

279-281.    SeeNorites. 
Hypozoic  rocks,  245,  246. 

IDENTIFICATION,  chemical,  450. 
Idocrase,  hollow  crystal  of,  212. 
Igneous  rocks,  theory  of,  1, 3, 4, 6.  See 

Exotic  rocks. 
Indigenous  rocks,  33,  193. 
Internal  heat.    See  Heat,  internal. 
Interpenetration    in    chemistry,    428, 

450. 
Inverted  strata  In  the  Alps,  334,  337 ; 

at  Troy,  New  York,  407 ;  at  Quebec, 

413. 
lodate  of  calcium  in  sea-water,  237. 


LA  BAIE  DU  FEBVRE,  waters  of,  124. 

Labrador,  geology  of,  261,  393. 

Labradorite  rocks,  29,  31,  33,  67,  278  - 
281.  See  Norian  rocks. 

Lake  Elton,  water  of,  83. 

Lambertville,  New  Jersey,  eruptive 
rocks  of,  186. 

Lanoraie,  water  of,  123. 

Laurent,  A.,  on  divisibility  of  formulas, 
431 ;  on  isomorphism,  422 ;  on  chem- 
ical types,  463. 

Laurentian  series,  29,  30,  206;  evi- 
dences of  life  in,  302;  eruptive  rocks 
of,  33;  vein-stones  of,  208-218. 

Laurentian,  Upper.    See  Norian. 

Laurentides,  243. 


Iodine  in  mineral  waters,  143;  its  rela-  Lauzon  formation,  259,  401,  411,  413. 


tion  to  earthy  sediments,  143,  226; 

in  sea- water,  143,  226,  237;  Sonstadt 

on,  237. 
lolite  or  dichroite,  28;  and  aspasiolite, 

315;  a  feldspathide,  445. 
Iron  in  mineral  waters,  128,  142. 
Iron  ores,  origin  of,  10,  13,  22,  29-31, 

97,  227-229,  243;  are  evidences  of 

life,  13,  302  ;  relations  of,  to  mineral 

coal,  229.     See  Bauxite. 
Iron  pyrites,  origin  of,  230,  232. 
Isomorphism,  432,  440  ;  its  relations  to 

pseudomorphism,    315  ;    polymeric, 

291,  315,  318,  442. 

JACKSON,  CHARLES  T.,  on  the  White 

Mountains,  241,  275. 
Jade  and  jadeite,  445,  446. 
Jollyte,  338. 
Joly,  water  of,  126. 


Jukes,  J.  B.,  on  mountains,  74  ;  on  Lime-soda  feldspars,  their  possible  ori- 


Cambrian  and  Silurian,  424. 

KANT  on  chemical  union,  428,  450. 
Kaolin,  its  formation,  10,  99-101,  445. 
Keferstein,  C.,  on  igneous  rocks  and 

volcanoes,  16,  62,  71,  77;  on  Mont 

Blanc,  338. 
King  and  Rowney  on  pseudomorphism,  j 

325. 

Kinnekulle,  Sweden,  geology  of,  367. 
Kolbe  on  chemical  types,  459. 
Kopp,  H.,  on  equivalent  volumes,  433, 

434. 


LeConte,  Joseph,  on  dynamic  geology, 

70-76. 

Leonhard  on  eruptive  limestones,  218. 
Lersch,  Hydro-Chemie,  122. 
Lesley,  J.  P.,  on  mountains,  52,  53;  on 

an  apparent   discordance   in  lower 

palaeozoic,  414. 
Lethaea  Suecica,  366. 
Leucite,  67,101,  210. 
Levis    formation,    259,  401,  413;    its 

fauna,  411,  412,  416. 
Leymerie  on  the  origin  of  limestones,  82. 
Liassic  fossils  in  veins,  203. 
Lignites,  176,  177,  181. 
Lime- salts  in  the  modern  ocean,  107, 

117, 119;  in  ancient  oceans,  2, 11,  41, 

82,  108,  109,  117;  in  mineral  waters, 

138.      See  Carbonate  of  lime    and 

Carbonate  of  magnesia. 
Lime,  silicates  of,  31,  151,  152. 


gin,  97.    See  Feldspars,  triclinic. 

Limestones,  Laurentian,  206 ;  of  White 
Mountain  series,  196,  244;  supposed 
eruptive,  21 8';  origin  of,  82,  311;  rela- 
tions of,  to  organic  life,  311.  See 
Carbonate  of  lime. 

Limonite,  organic  matter  in,  98. 

Lingula,  a  phosphatic  shell,  312. 

Lingula  flags,  266,  370,  371,  374. 

Liquids,  equivalent  volume  of,  436. 

Logan,  W.  E.,  on  Upper  Laurentian, 
29,  279;  on  the  Appalachians,  257; 
on  the  White  Mountains,  276  ;  on 


INDEX. 


483 


lower  palaeozoic  rocks,  262  ;  on  the  [Marls,  magnesian.    See  Sepiolite. 
geology  of  Quebec,  256-258,   397 -  Marsh  gas,  origin  of,  177,  182;  relation 
899  ;  on  the  Quebec  group,  259,  263,  |    of,  to  radiant  heat,  46. 
264,  401,  403;  on  the  geology  of  Ver-  Mather  on  limestones,  218;  on  Taconic 


mont,  260,  894 ;  on  geological  nomen- 
clature in  Canada,  420. 

Loire,  waters  of,  84. 

Longmynd  rocks,  266,  380,  382. 

Loraine  shales.  See  Hudson  River 
gronp.  " 

Lory  on  the  geology  of  the  Alps,  334, 
336. 

Lower  Helderberg  rocks,  415,  418. 

Lower  palaeozoic  formations,  classifica- 
tion of,  267 ;  tabular  view  of,  386. 

Ludlow  rocks,  353,  361,  362,  418. 

Luxeuil,  water  of,  205. 

Lycopodium,  spores  of,  181. 

Lyell,  C.,  on  the  cause  of  plications  in 
strata,  55;  on  Mont  Blanc,  338. 

MACCULLOCH  on  hypersthene  rocks, 
279. 

Macfarlane,  T.,  on  Huronian  rocks, 
18,  269,  274;  on  the  plutonic  origin 
of  crystalline  schists,  294. 

Mac  vicar  on  the  constitution  of  min- 
eral species,  457. 

Madoc,  gold  and  carbon  of,  217. 

Magnesian  marls,  see  Sepiolite  ;  mi- 
ca, 207;  silicates,  formation  of,  21, 
122,  151,  296,  297,  300. 

Magnesite,  33,  90,  243. 

Magnesium  salts    in  mineral  waters, 


rocks,  254. 

Matinal  rocks,  421. 

Matter,  its  chemical  history,  426,  465. 

Matthews,  G.  F.,  geology  of  New  Bruns- 
wick, 407. 

Meionite,  445,  446. 

Melting-point,  relation  of,  to  pressure, 
7,  39,  60,  65. 

Menevian  rocks,  266,  371  -  373  ;  hi 
North  America,  385,  407. 

Metagenesis  in  chemistry,  427,  465. 

Metalliferous  deposits,  origin  of,  23, 
220. 

Metals  in  sea-water,  231. 

Metamorphic  rocks,  objections  to  the 
term,  18;  chemistry  of,  19. 

Metamorphism  of  rocks,  9,  18,  19,  24- 
28,  286,  287,  291,  298-300,  305-307, 
317,  320;  not  to  be  confounded  with 
pseudomorphism,  24,  291 ;  Hutton 
and  Boue  on,  24,  321 ;  Dana  on,  291, 
320;  Credner  and  Giimbel  on,  305; 
Favre  on,  342,  347 ;  Nauraann  on,  25, 
293,  295,  322,  323;  local,  18,  24-26, 
295,  298,  299,  307. 

Metamorphosis  of  rocks,  supposed,  il- 


lustrations 
324  -  326. 


of    the    doctrine,    287, 


Metamorphosis  in  chemistry,  427,  465. 
Meteoric  stones,  constitution  of,  302. 


137,  138;  chloride  of,  117,  118;  sul-  Micas,  conditions  of  their  formation,  28; 


phate  of,  106,   108,   119,   134.    See 
Carbonate  of  magnesia. 
Magnetic  iron  ore,  in  vein-stones,  214 ; 
veins  in,  215.     See  Iron  ores. 


Magnetism,  its  relation  to  the  earth's  Michigan,  crystalline  rocks  of,  274. 


interior,  60,  61. 

Mallet,  R.,  on  internal  heat,  78;  on  vol- 
canic rocks,  79. 

Malvern,  geology  of,  360,  373,  383. 

Manganese,  relations  of,  to  vegetation, 
98  ;  in  waters,  142. 

Manitoulin  Island,  water  of,  158. 

Marbles  of  Vermont,  311. 

Marcou,  J.,  on  Taconic  rocks,  251. 

Marignac  on  dolomites,  309. 

Marine  salts  in  rocks,  108. 


magnesian,  of  Laurentian  series,  207. 
Mica-schists,    28,    32,   207,    244-247, 
272,  282,   326,  331,  353,  408;   sup- 
posed pseudomorphic  origin  of,  326. 


Mineralogj',  its  province,  453 ;  classifi- 
cation in,  454. 

Mississippi,  mud  of,  10;  valley,  geology 
of,  50,  75. 

Mixtures  in  mineral  species,  444. 

Molasse  of  the  Alps,  345. 

Montalban  rocks,  194,  282.  See  White 
Mountain  series. 

Montarville,  dolerite  of,  186. 

Mont  Blanc,  geology  of,  329;  trias  of, 
331;  crystalline  rocks  of,  330. 


484 


INDEX. 


Mont  Cenis  Tunnel,  334,  347. 

Montlosier,  De,  on  mountains,  52,  74. 

Montreal,  dolerite  of,  186,  298. 

Moore,  Charles,  on  liassic  fossils  in 
veins,  204. 

Morlot,  Von,  on  dolomite,  308. 

Mountains,  origin  of,  49,  51,  52,  73,  74; 
synclinal  structure  of,  345. 

Mud-volcanoes,  8. 

Murchison,  R.  I.,  on  geology  of  Scot- 
land, 271;  on  Silurian  rocks,  352, 
355,  378-380;  errors  of  his  Silurian 
sections,  358,  362,  380;  on  geology 
of  the  Alps,  337. 

Murray,  Alex.,  on  geology  of  New 
foundland,  406. 

NATROLITE  and  orthoclase  associated, 
5, 192,  206. 

Natron-lakes,  12,  85,  146,  158. 

Naumann,  C.  F.,  on  metamorphism, 
25,  293,  295,  322,  323;  on  envelop- 
ment, 292;  on  origin  of  crystalline 
rocks,  294;  on  pseudomorphism,  292, 
320,  322. 

Nebular  hypothesis,  36,  38,  222. 

Neolite,  296. 

Neptunists  and  plutonists,  45. 

Nerepis,  New  Brunswick,  granites  of, 
201. 

Nevada,  silicious  veins  in,  204. 

Newberry,  J.  S.,  on  cycles  of  sedimen- 
tation, 241 ;  on  geology  of  Ohio, 

New  Brunswick,  geology  of,  275,  407  - 
409,  415. 

Newfoundland,   geology  of,  261, 
405-410. 

New  Hampshire,  geology  of,  242,  281. 

Newport,  Rhode  Island,  geology  of,  249. 

New  York,  geological  survey  of,  387  - 
389 ;  system  of  rocks,  387,  389 

Niagara  limestone,  417,  418 ;  of  Chicago, 
172. 

Nickel  in  rocks,  31,  32,  34,  243,  247, 
269. 

Nickles,  J.,  on  nitrification,  472. 

Nicol,  on  geology  of  Scotland,  271. 

Nicolet,  Quebec,  water  of,  126. 

Nitrates,  reduction  of,  94, 113,  472 

Nitre,  hollow  crystals  of,  212. 

Nitrification,  theory  of,  464,  470. 


Nitrite  of  ammonia,  its  formation,  471. 
Nitrogen  gas,  a  nitryl,  464,  470. 
Nitrogen  of  volcanoes,  8 ;  amount  of,  in 

rocks,  113. 

Norian  rocks,  29,  31,  33,  278-282. 
Norites,  31,  33,  279 ;  olivine  in,  31,  280. 
Nova  Scotia,  geology  of,  408,  409,  415. 
Nucleus  of  the  earth,  7,  39,  44,  56,  57, 

59-61,  64. 

OCEAN,  primitive,  2, 11,  40,  41 ;  palaeo- 
zoic, 82,  104,  108,  109,  119,  137,  163; 
evaporation  of  its  waters,  76,  83,  92, 
104,  107,  108,  310;  metals  in  waters 
of,  231,  237;  bromine  in,  142;  iodine 
in,  144,  226,  237  ;  potash  in,  135.  See 
Carbonate  of  soda  and  Carbonate  of 
lime. 

Ochre,  formation  of,  98,  228.  See  Iron 
ores. 

Ohio,  brines  of,  120;  geology  of,  416. 

Oken,  mineralogical  classification  of, 
454. 

Oleiferous  limestone  of  Chicago,  172. 

Olivine,  in  norites,  31,  280.  See.  Chrys- 
olite. 

Oneida  conglomerate,  416. 

Onondaga  formation,  155,  417,  418;  the 
oldest  saliferous  known,  119;  min- 
eral waters  from,  163. 

Ontario,  petroleum  of,  168-171. 

Ophiolite.     See  Serpentine. 
416.  Orbicula,  a  phosphatic  shell,  312. 

Ore-deposits,  23,  233. 

Organic  and  inorganic  bodies,  427, 453. 
275,  Organic  life,  chemical  relations  of,  2, 
13,  22,  42,  96,  144,  225,  226,  231,  302, 
311, 312  ;  evidences  of,  in  crystalline 
rocks,  13,  302;  in  aerolites,  302. 

Organic  matters  in  waters,  94, 125, 152, 
153;  chemical  relations  of,  13,  22, 
97  -  99. 

Orthoclase,  12,  101,  192,  206;  produc- 
tion of,  298,  299;  formula  of,  443. 
See  Feldspars,  Granites  and  Granitic 
vein-stones. 

Orthophyre,  187,  243,  250,  282. 

Ottawa  basin,  geology  of,  412. 

Ottawa  River,  water  of,  84, 126 ;  potash 
in,  136 ;  silica  in,  150 ;  silicate  of  lime 
from,  152. 


INDEX. 


485 


Owen,  D.  D.,  geology  of  Wisconsin, 

403. 

Oxychloride  minerals,  442. 
Oxygen,  equivalent  weight  of,  176, 431 ; 

active,  see.  Ozone. 
Ozone,  relation  of,  to  radiant  heat,  46 ;  a 

triple  molecule,  464;  production  of, 

470 ;  relation  of,  to  nitrification,  471. 


PAL^OTROCHIS,  411. 

Palaeozoic  sediments,  origin  of,  10,  75. 

Palaeozoic  formations  of  St.  Lawrence 
basin,  154;  of  North  America  and 
England,  thickness  of,  50,  377 ;  tabu 
lar  view  of  lower,  386.  See  Cambrian 
and  Silurian. 

Palaeozoic  climate.     See  Climate. 

Palaeozoic  ocean.    See  Ocean. 

Paradoxides  Harlani,  405. 

Paragonite,  244. 

Paraffines  of  petroleum,  182. 

Paris,  France,  magnesian  sediments  of, 
296. 

Paris,  Maine,  granitic  vein  of,  195; 
tourmalines  of,  200,  212. 

Peat,  94, 181. 

Pebbles  in  veins,  204. 

Pennsylvania,  geology  of,  245 ;  geologi- 
cal survey  of,  420. 

Peristerite,  214. 

Perthite,  214,  444. 

Petalite,  210 ;  formula  of,  443. 

Petrol  ia,  Ontario,  waters  of,  161. 

Petroleum,  168;  surface  wells  of  in  On- 
tario, 171;  of  Chicago,  172-174;  An- 
drews on,  174;  of  vegetable  or  ol 
animal  origin,  179;  hydrocarbon 
gases  accompanying,  182. 

Phillips,  J.  A., 
vada,  204. 

Phillips,  John,  on  igneous  rocks,  3,  24 
66 ;  on  rocks  of  Anglesea,  270 ; 
ogy  of  Malvern,  360,  370,  383. 

Phosphates  in  waters,  94-96, 142; 
centration  of,  225 ;  relations  to  organ- 
isms, 312. 

Phosphatic  shells,  312. 

Phosphoric  acids,  genesis  of,  466. 

Phosphorus,  its  diffusion  in  nature, 
222. 

Plants.    See  Organic  life. 


Plasticity  of  rocks,  4,  9,  44,  65,  72, 
189-191. 

Playfair  and  Joule  on  equivalent  vol- 
umes, 434,  440,  457. 

Plication  of  rocks,  17,  65,  57,  72. 

Plombieres,  water  of,  25,  205,  297. 

Plutonic  origin  of  stratified  rocks,  186, 
294. 

Plutonic  rocks,  sedimentary  origin  of, 
8, 14,  43,  67,  317.  See  Exotic  rocks. 

Plutonists,  65 ;  and  neptunists,  45. 

Point  Levis,  Quebec,  geology  of,  396, 
397.  See  Levis. 

Polybasic  acids,  their  genesis,  464, 466. 

Polymeric  types,  464,  466 ;  isomor- 
phism. See  Isomorphism,  polymeric. 

Polymerism  in  mineral  species,  446, 
457. 

Porosity  of  rocks,  103 ;  determination 
of,  164 ;  table  of,  166. 

Porphyry,  quartziferous.  See  Ortho- 
phyre. 

Potash,  21,  22 ;  fixity  of  compounds  of, 
12,  22,  95 ;  how  removed  from  ocean, 
22,  137,  144,  226;  rare  in  ancient 
seas,  137;  occurrence  of,  in  natural 
waters,  126,  135-137. 

Potsdam  formation,  254,  260,  262,  266, 
268,  389,  403 ;  Upper  and  Lower,  266 ; 
mineral  waters  from,  156. 

Pratt  on  the  solidity  of  the  earth,  44. 

Precipitation  of  sediments,  influence  of 
salts  on,  10. 

Predazzite,  its  relation  to  gypsum,  107, 
133. 

Pressure,  its  relations  to  fusion  and  so- 
lution, 7,  39,  65,  66,  204. 

Primal  rocks  of  Rogers,  255,  421. 

,  266, 368. 
378.    See  Silurian,  primordial. 

Progressive  series  in  chemistry,  439. 

Protogine  of  Mont  Blanc,  330. 

Protozoic  rocks,  364. 

,m  defined,  24, 286  -  294 ; 
Dana  on,  287,  291,  319,  320,  322; 
Delesse  on,  288,  292,  314-318;  Nau- 
mann  on,  292,  322 ;  Scheerer  on,  291, 
323 ;  Warrington  Smyth  on,  313,  324 ; 
illustrations  of,  324-326. 

Pumpelly,  R.,  orthophyres  of  Missouri, 
250. 


silicious  deposits  of  Ne-  Primordial  rocks  of  Barrande, 


con-  Pseudomorphisi 


486 


INDEX. 


Pyrites,  iron,  origin  of,  230. 
Pyrognomic  minerals,  5. 
Pyrophyllite  rocks,  28. 
Pyroschists,  169, 176-179. 
Pyroxene,  25, 186,  215,  216. 
Pyroxenites,  31,  207. 

QUARTZ,  its  origin,  2;  conditions  of 

crystallization,  6,  204,  205;  chalce- 

donic,  89;  crystalline  sands  of,  89; 

veins  of,  192  - 194, 196, 199 ;  rounded 

crystals  of,  213. 

Quartzite,  supposed  intrusive,  242. 
Quebec  geology  of,  256 -259,  390,  396- 

403  ;  probably  inverted  section  at, 

413. 
Quebec  group,  155,  259,  398,  401; 

relation  to  the  Trenton,  413 ;  mineral 

waters  from,  155. 
Quincite,  296. 

RADICLES  in  chemistry,  428,  466,  467. 
Ramsay,  A.  C.,  on  dolomites,  92;  on 

stratigraphical  breaks,   376;  on  the 

geology  of  North  Wales,   374,  380, 

381,  383. 
Red  sandrock  of  Vermont,  260,  390, 

391,  394. 

Rivers,  waters  of,  84-86,  126 
Rocks,  porosity  of,  103,  164;  subaerial 

decay  of,  2,  10,  41,  101-103;  recom- 

posed,  251,  285,  339,  341. 
Rogers,  H.  D.,  on  crystalline  rocks  of 

Pennsylvania,  245 ;  on  laconic,  254 ; 

on  Cambrian,  374,  381,  422. 
Rogers,  H.  D.  and  W.  B.,  on  geology 

of  the  White  Mountains,  242,  276 ;  on 

nomenclature    of  palaeozoic    rocks, 

420-422. 
Rogers,  W.  B.,  on  geology  of  Virginia, 

275;  on  protozoic  rocks  in  Massa- 
chusetts, 405. 

Rounded  crystals,  212,  213. 
Royal  Institution,  45. 
Rutland,  Vermont,  geology  of,  265. 

SAFFORD  on  geology  of  Tennessee,  255. 
Saginaw,  Michigan,  brines  of,  120. 
Salina  formation.    See  Onondaga. 
Salter,   J.  W.,   on   geology  of  North 
Wales,  354,  362,  364,  371,  372. 


Salt  wells  of  Goderich,  Ontario,  204. 

Sands,  silicious,  crystalline  and  chalce- 
donic,  89. 

Salt  lagoons,  86. 

Saratoga,  waters  of,  102,  149. 

Saussurite,  445. 

Scandinavia,  geology  of,  209,  257,  263, 
266-269,376,385.  • 

Scapolite,  28,  101,  210,  446. 

Schaeflfer,  G.  C.,  on  nitrification,  472. 

Scheerer,  Th.,  on  granites,  5,  65,  189; 
on  envelopment  of  minerals,  291 ;  on 
polymeric  isomorphism,  291,  315, 
318,  442. 

Schiel,  James,  on  progressive  series  in 

chemistry,  439. 
its  Schonbein  on  nitrification,  471. 

Scotland,  Highlands,  geology  of,  34, 
271,  272,  338. 

Scrope,  Poulett,  on  water  in  igneous 
rocks,  5,  65,  66,  190;  on  volcanoes, 
60. 

Sea-salt,  its  origin,  2,  12;  its  deposi- 
tion, 76,  83,  86,  107,  120,  310. 

Sea-water.     See  Ocean. 

Sea-weed.    See  Fucoids. 

Sedgwick,  A.,  on  geology  of  Anglesea, 
270,  273 ;  of  North  Wales,  350  -  365 ; 
on  the  Cambrian  series,  see  Cam- 
brian ;  on  recomposed  rocks',  341  ; 
on  systems  in  geological  classifica- 
tion, 377 ;  his  views  misrepresented, 
357,  364,  365  ;  his  classification  of 
lower  palaeozoic  rocks,  384 ;  his 
death,  349. 

Sediments,  sources  of,  10,  49,  75;  re- 
lated to  mountains,  51,  73;  conden- 
sation of,  by  heat,  56,  71 ;  conversion 
of,  to  crystalline  rocks,  4,  7-9,  14- 
16,  25-27,  43,  56,  57,  62-64,  284, 
285,  317. 

Selwyn,  A.  R.  C.,  on  deposition  of  gold, 
237 ;  on  geology  of  Victoria,  Austra- 
lia, 273 ;  on  geology  of  Nova  Scotia, 
408. 

Senarmont,  H.  de,  on  artificial  forma- 
tion of  minerals,  221. 

Sepiolite,  123,  296,  300 ;  its  relations  to 
steatite,  317,  318.  See  Magnesian 
silicates. 

Serpentine,  Laurentian,  31, 34 ;  of  Green 


INDEX. 


487 


Mountain  series,  32, 34,  243 ;  Silurian  Soda.   See  Carbonate  of  Soda  and  Sea- 

of  Syracuse,  N.  Y.,  310;  in  tertiary     salt. 

sediments,  303 ;  an  indigenous  rock,  Soils,  the  chemistry  of,  22, 95,226-228. 

249,  250,  285,317;  of  aqueous  origin, |  Solution   chemically  considered,  429, 

123,  297,  300,  318;  regarded  as  an|    448;    its   relation   to   pressure,   see 

eruptive  rock,  242, 247, 249, 316,  336  ;|    Pressure. 

its  supposed  pseudomorphous  origin,!  Sonstadt  on  sea-water,  237. 

287,  291,  316-319,  325;  its  supposed  Sorby,  H.  C.,  on  liquids  in  crystals,  65, 


conversion  into  carbonate  of  lime, 
825;  Dana  on,  319,320;  Delesse  on, 


316,  317;    Credner  on,  304;    Favre  Spectroscopic  studies  of  celestial  bodies, 


on,  348. 

Serpulites,  a  phosphatic  shell,  312. 

Shaler,  N.  S.,  on  volcanoes,  60 ;  on  An- 
ticosti  group,  416. 

Shales,  bituminous.     See  Pyroschists. 

Shawangunk  conglomerate,  416. 

Sherbrooke,  Nova  Scotia,  granite  vein 
of,  198. 

Silica,  sources  of,  2,  10,  150 ;  how  re- 
moved from  waters,  22 ;  relations  to 
organic  life,  22.  312;  deposits  of,  89, 
204,  234.  See  Quartz. 

Silica  and  silicates  in  waters,  12, 21, 25 
84,  95,  105. 

Silicate  of  lime  from  waters,  149, 151  - 
153;  its  action  on  magnesian  salts 
122. 

Silicate  of  magnesia  from  waters.  See 
Magnesian  silicates. 

Silicification  of  fossils,  89,  286. 

Sidellon  the  precipitation  of  clays,  10. 

Silver  in  sea-water,  its  separation  from 
and  concentration,  231,  235. 

Sillery  formation,  256,  401,  411. 

Silurian  system,  352,  365, 379-381,  423 
425;  Primordial,  369  378,  423;  Low- 
er, 355-357,  363,  364,  378,  418,  420: 
Middle,  417,  418,  423;  Upper,  355 


415, 418, 424;  nomenclature  in  Amer-  Streng  on  igneous  rocks,  3. 


ica,  419,  420. 
Siluro-Cambrian,  423,  424. 
Sismonda,  geology  of  the  Alps,  334, 348 
Skaraborg,  geology  of,  366. 
Skeleton  crystals,  201,  211. 
Skiddaw,  geology  of,  273,  284,  412. 
Skye.  Isle  of,  norites  of,  34,  281. 
Smith,  J.  Lawrence,  on  silicate  of  lime 

from  waters,  151. 
Smyth,    Warrington,    on    pseudomor 

phism,  313,  324. 


205 ;  on  the  relations  of  pressure  to 
solution,  65,  204. 


35,  222. 

Spinel,  supposed  alteration  of,  289. 
Springs,  mineral.      See  Chemistry  of 

Natural    Waters,    contents    of    the 

various  parts,  pages  93,  116,  135. 
Stallo,  J.  B.,  on  chemical  theory,  450, 

455. 
Staurolite-bearing  rocks,  28,  272,  282, 

331,  408. 

St.  Albans,  Vermont,  geology  of,  264. 
St.  Catherine,  Ontario,  water  of,  116. 
St  Davids,  Wales,  geology  of,  373,  375, 

382. 
St.  John,  New  Brunswick,  geology  of, 

406,  407. 
St.  Lawrence  basin,  mineral  waters  of, 

153,  158 ;  river,  water  of,  136,  150. 
St.  Leon,  Quebec,  water  of,  123. 
St.  Ours,  Quebec,  water  of,  136. 
Stearine,  its  equivalent  weight,  456. 
Steatite,  32,  243,  247,  249, 250, 269,  272, 

297,  300,  318,  330,  331,  334,  342;  its 

supposed  eruptive   origin,  249;    its 

supposed  pseudomorphic  origin,  319, 

320,  322,  325. 

Ste.  Genevieve,  Quebec,  water  of,  143. 
Stratigraphical  breaks,  262,  376,  377, 

413,  414. 


Stromatopora,  Dawson  on,  411. 

Strontia  in  waters,  141;  sulphate  of, 
87,  117. 

Sulphates,  their  constitution,  467;  de- 
composition of,  by  heat,  108,  112; 
reduction  of,  87,  99,  145,  163,  230; 
absence  of,  from  some  saline  waters, 
117,  144,  159.  See  Gypsum,  also 
Alumina  and  Magnesia,  sulphates  of. 

Sulphur,  as  a  triple  molecule,  464 ;  na- 
tive, origin  of,  23,  87,  99,  111. 


488 


INDEX. 


Sulphurets,    origin    of,   23,   111,   230; 

soluble,  in  natural  waters,  145,  159  - 

163 ;  action  of,  on  clays,  99. 
Sulphuretted  hydrogen,  8,  15,  87,  99, 

163,  230. 

Sulphuric  acid  in  waters,  111,  112, 130. 
Sulphurous    acid,    origin    of,    8,    15, 

111. 

Sun,  constitution  of,  36,  37. 
Sweden,  geology  of.    See  Scandinavia. 
Syenite  denned,  184,  185. 
Syracuse,  New  York,  brines  of,  119; 

serpentine  of,  310. 

TABLE,  of  porosity  of  rocks,  166;  of 
lower  palaeozoic  formations,  386. 

Tachydrite,  108,  118. 

laconic  system,  155,  251-254,  264, 
326,  388,  389,  391,  394;  fauna  of,  257, 
391;  distinguished  from  primary, 
251,  326;  synonymous  with  Lower 
and  Middle  Cambrian,  389. 

Talc.     See  Steatite. 

Talcose  schists,  244-249,  251,  330- 
338,  341,  343,  383;  their  supposed 
pseudomorphic  origin,  316,  320,  325. 

Temperature  of  Earth's  surface,  see 
Climate ;  of  Earth's  interior,  see 
Earth,  its  interior. 

Tennessee,  copper  veins  of,  217,  250; 
geology  of,  255. 

Terranovan  series,  194,  275,  276.    See 
Montalban  and  White  Mountain 
ries. 

Terrestrial  circulation,  22,  225,  235. 

Teton  Mountains,  geology  of,  262. 

Thenardite,  its  formation,  108. 

Thermal  waters,  157. 

Thompson,  Sir  William,  on  the  earth's 
interior,  44,  77. 

Tin,  238.     See  Cassiterite. 

Titanium,  31,  192,  200,  210,  238,  251, 
280. 

Topsham,  Maine,  veins  of,  194. 

Tourmaline,  195,  200,  212. 

Trachytes  of  Canada,  185. 

Transmutation  of  minerals,  313,  325. 

Travertines,  origin  of,  89. 

Trebra,  Von,  on  altered  rocks,  339. 

Tremadoc  rocks,  353,  369-372,  374- 
376,  381,  412. 


Trenton  formation,  256,  412-414,  417; 
mineral  waters  from,  116,  123,  124, 
155,  156,  158. 

Treve  on  magnetism,  61. 

Troy,  New  York,  geology  of,  407. 

Trinidad,  bitumen  of,  176. 

Tschermak  on  feldspars,  444. 

Tuscarora,  Ontario,  water  of,  130. 

Tyndall,  J.,  on  heat-radiation  and  cli- 
mate, 42,  46. 

URSCHIEFER  of  Scandinavia,  age  of, 

18,  269 ;  gypsum  in,  336. 
Utica  formation,  256,  421 ;  a  pyroschist, 

178;  mineral  waters  from,  124,  156, 

157. 

VALORSINE,  Switzerland,  conglomer- 
ate of,  339. 

Vapors,  relations  of,  to  solids  and 
liquids,  456. 

Varennes,  Quebec,  waters  of,  124. 

Vegetable  matter.    See  Organic  matter. 

Vegetation.    See  Organic  life. 

Veins,  distinguished  from  dikes,  193, 
202;  fossils  in,  203;  pebbles  in,  204; 
banded  structure  of,  193,  211 ;  forma- 
tion of,  233 ;  recent  origin  of  some, 
234.  See  Granitic  vein-stones  and 
analysis  of  Essay  XL,  183. 

Vermont,   geology  of,  256-266,  390- 

395,  402. 

se-  Verneuil,  De,  on  American  palaeozoic 
rocks,  419. 

Vichy,  water  of,  85. 

Victoria,  Australia,  geology  of,  273. 

Virginia,  geology  of,  249,  255,  275,  407. 

Vital  forces,  224,  235. 

Voelcker,  action  of  water  on  soils,  95. 

Voellknerite.  289. 

Volcanoes,  phenomena  and  causes  of, 
8,  15,  44,  62-64,  77,  111;  interven- 
tion of  water  in,  5,  61,  63,  65 ;  distri- 
bution of,  and  relations  to  the  newer 
formations,  9,  17,  67,  67,  68,  71;  his- 
torical relations  of,  68;  Hall  on,  58; 
Herschel,  J.  F.  W.,  on,  8,  15,  44,  56, 
62,  71;  Keferstein  on,  16,  56,  62,  71; 
LeConte  on,  72,  77 ;  Mallet  on,  78,  79. 

Volger  on  the  filling  of  veins,  202 ;  on 
pseudomorphism,  287,  324,  325. 


INDEX. 


489 


Volumes,  combining,  429;  equivalent, 

435,  438-443. 
Vose,  G.  L.,  on  internal  heat  of 

earth,  78. 


WATER  as  a  chemical  type,  461,  465, 
468;  solvent  powers  o/,  5,  6,  35,  94, 
223;  they  are  increased  by  pressure, 
65,  204,  223;  in  the  formation  of 
granitic  rocks,  6,  33,  65,  189,  190; 
cohesion  of,  diminished  by  salts,  10. 

Waters,  action  of,  on  soils  and 
ments,  12,  22,  27,  95,  284 ;  chemistry 
of,  21-23;  mineral,  geological 
tions    of,    154-158.      See  analysis 
of  Essay  XL,  93,116,  135. 

Water-lime  formation,  418. 

Way,  action  of  waters  on  soils,  95. 

Websterite,  98. 

Whitby,  Ontario,  water  of,  116,  142. 

White,  C.  A.,  on  decomposition  of  crys 
talline  rocks,  250. 

White  Mountain  rocks,  32,  188,  217, 
242-244,  271-276,  282,  327;  granite 


veins  of,  194,  217;  supposed  palaeo- 
zoic age  of,  276. 

the  Whitney,  J.  D.,  orthoclase  of  Lake  Su- 
perior, 192. 

Williamson   on  the  water-type,  462, 
468. 

Wind-River  Mountains,  geology  of,  262. 

Wing,  Aug.,  on  geology  of  Vermont, 
265. 

Woodward  on  Cambrian  and  Silurian, 

381. 
sedi- Woody  tissues,  their  change  to  coal, 

177,  181. 

rela-  Wurtz,  Ad.,  on  chemical  types,  460, 
468 ;  on  radicles,  466. 

Wurtz,  Henry,  on  a  source  of  internal 
heat,  78 ;  on  gold  in  sea-water,  238. 


ZEOLITES,  solubility  of,  5 ;  modern  ori- 
gin of  some,  25,  205,  297,  298 ;  asso- 
ciation of,  with  orthoclase,  5,  192, 
206 ;  are  hydrous  feldspars,  298. 

Zinciferous  minerals  of  New  Jersey, 
215. 


THE    END. 


Cambridge :  Electrotyped  and  Printed  by  Welch,  Bigelow,  and  Company. 


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